Back-end Facility Research Articles

Evaluation of HackLearn COFELET Game User Experience for Cybersecurity Education

HackLearn is a scenario-based hacking simulation game for teaching cybersecurity concepts while providing hands-on hacking experiences to the learners. HackLearn design is based on the COFELET framework, which assimilates modern learning theories, well-known cybersecurity standards, and built-in scaffolding and assessment features. Aiming at evaluating the user experience perceived by HackLearn’s users, we describe the process of adopting it in a real educational environment based on the didactic framework for simulation games. Additionally, we present the evaluation methodology elaborated, based on the serious games’ quality characteristics framework. We discuss the evaluation results which indicate that HackLearn is engaging, motivating, usable and effective in teaching cybersecurity concepts and hacking strategies and techniques. The evaluation results revealed the HackLearn’s aspects that can be improved such as the scaffolding feature and the communication mechanism with the game’s back-end facility. The presented work validates and finalizes prior work elaborated on the COFELET framework (e.g., COFELET ontology and the COFELET games life-cycle), whereas it provides directions for future work in the development and evaluation of cybersecurity serious games.

ІСТОРІЯ НИЗЬКОЧАСТОТНИХ ДОСЛІДЖЕНЬ ПУЛЬСАРІВ

Purpose: The main most pronounced events, which occurred in the initial period of the pulsars’ study at the decameter wavelength range, are presented. The example of the main scientific problems, which were formulated at the very beginning of pulsar research, shows how the emphasis and priorities of these studies have been changing over time, which tasks have finally been solved, and which are still waiting to be solved. It is shown how the ongoing modernization of the UTR-2 radio telescope have allowed to acquire new qualities in astrophysical research being made with this radio telescope and to identify new scientific directions. The example of the cited references shows how the pulsar research efforts in Ukraine have been developed and how they were integrated into the world astrophysical research of these unique objects. The purpose of this work is to show the relationship between the past and the present on the example of pulsars for longer than a semi-centennial period and to show how the scientific problems that were formulated in the past, and which could not be solved under the then-existing technical conditions, were solved by the subsequent generations of researchers. Design/methodology/approach: The methods of comparison and historical parallels show how the low-frequency studies of pulsars have been developed and evolved almost from their discovery until now. Findings: It is shown how quantitative transformations and technical development, as well as non-standard scientific approaches, unhackneyed thought and international cooperation allow to solve complex radio astronomical problems related to the low-frequency studies of pulsars. Conclusions: The paper provides a historical overview of more than half a century-long radio astronomical studies of pulsars, having been and still being made at the decameter band using the UTR-2 radio telescope. The “old” and current priorities in pulsar research are given, and it is shown how qualitatively the technical parameters of back end facility and computer performance have been changed in studying the coherent pulsar radio emission nature. Key words: aberration; frequency band; pulse; interpulse; dispersion measure; rotation measure; plasma; pulsar; radio telescope

Stochastic optimization of product–machine qualification in a semiconductor back-end facility

In order to process a product in a semiconductor back-end facility, a machine needs to be qualified, first by having product-specific software installed and then running test wafers through it to verify that the machine is capable of performing the process correctly. In general, not all machines are qualified to process all products due to the high machine qualification cost and tool set availability. The machine qualification decision affects future capacity allocation in the facility and subsequently affects daily production schedules. To balance the tradeoff between current machine qualification costs and future potential backorder costs due to not enough machines qualified with uncertain demand, a stochastic product–machine qualification optimization model is proposed in this article. The L-shaped method and acceleration techniques are proposed to solve the stochastic model. Computational results are provided to show the necessity of the stochastic model and the performance of different solution methods.

Batch Production Scheduling for Semiconductor Back-End Operations

A good production schedule in a semiconductor back-end facility is critical for the on time delivery of customer orders. However, the scheduling process is usually difficult due to the wide product mix, large number of parallel machines, product family-related setups, and high weekly demand consisting of thousands of lots. In this paper, we present a new mixed-integer-linear-programming (MILP) model for the batch production scheduling of a semiconductor back-end facility with serial production stages. Computational results are provided for finding optimal solutions to small problem instances. Due to the limitation on the solvable size of the MILP formulation, a deterministic scheduling system (DSS), including an optimizer and a scheduler, is proposed to provide suboptimal solutions in a reasonable time for large real-world problem instances. Small problem instances are randomly generated to compare the performances of the optimization model and the DSS. An experimental design is utilized to understand the behavior of the DSS under different production scenarios.

Design and validation of heuristic algorithms for simulation-based scheduling of a semiconductor Backend facility

A simulation-based scheduling system is discussed which was developed for a semiconductor Backend facility. Apart from usual dispatching rules it uses heuristic search strategies for the optimisation of the operating sequences. In practice hereby multiple objectives have to be considered, e.g. concurrent minimisation of mean cycle time, maximisation of throughput and due date compliance. Because the simulation model is very complex and simulation time itself is not negligible, we emphasise to increase the convergence of heuristic optimisation methods, consequentially reducing the number of necessary iterations. Several realised strategies are presented.

A working single-level trap model and a resistivity scaling law for the proton-induced high-resistivity silicon

A particle-enhanced isolation technology had previously been proposed to direct energetic proton flux on VLSI-processed mixed-mode IC wafers before packaging for the prevention of undesirable substrate coupling [C.P. Liao, D. Tang, H.C. Lu, Creation of local semi-insulating regions on semiconductor substrates, US Patent 6,046,109, April 4, 2000]. Results of an improvement of 25–30 dB in noise coupling suppression and a great enhancement of two to three folds on Q values of on-chip inductors had also been reported [C.P. Liao, M.N. Liu, K.C. Juang, Cross-talk suppression in mixed-mode IC's by the π technology and the future with a SOC integration platform: particle-beam stand (PBS), IEEE Trans. Electron Dev. 50 (3) (2003) 764 (special issue on RF and SOC); C.P. Liao, T.H. Huang, C.Y. Lee, D. Tang, S.M. Lan, T.N. Yang, L.F. Lin, Method of creating local semi-insulating regions on silicon wafers for device isolation and realization of high Q inductors, IEEE Electron Dev. Lett. 19 (12) (1998) 461–462; C.P. Liao, C.W. Liu, Y.M. Hsu, Observation of explosive spectral behaviors in proton-enhanced high- Q inductors and their explanations, IEEE Trans. Electron. Dev. 50 (3) (2003) 758 (special issue on RF and SOC)]. Today, continued improvement of this technology has led to a new VLSI back-end facility: the particle-beam stand (PBS), which may ultimately become the general SOC (system-on-a-chip) integration platform. However, so far the mechanism and TCAD model behind such an approach have yet to be quantitatively determined. In this work, the establishment of an effective, self-consistent, 1-level trap model is attempted through fitting the existing single-trap-level theory [J.L. Moll, Physics of Semiconductors, McGraw-Hill, New York, 1964 (Chapter 6)] with experimentally obtained parameters and the assistance from numerical simulations of the SRIM (The Stopping and Range of Ions in Matter) code [SRIM—The Stopping and Range of Ions in Matter, a computer code constantly updated by J.F. Ziegler, J.P. Biersack. Available from: 〈 http://www.srim.org/〉. A full description of the calculation is found in The Stopping and Range of Ions in Solids, by J.F. Ziegler, J.P. Biersack, U. Littmark, Pergamon Press, New York, 2003] (a charged-particle stopping-power calculation program). It is revealed that, more than merely simple traps of charge carriers, those proton-created defects are also intrinsically charged (carrying +e or −e) and thus all are participating in the Rutherford-like scattering of the remaining free charge carriers escaping the defect trapping. The found effective single trap levels ( E T) are about +0.24 eV in n-Si and −0.34 eV in p-Si, measuring from the middle of the energy bandgap. Finally, a scaling law for such proton-rendered resistivity enhancement is given.

A Scheduling Heuristic for Maximizing Wirebonder Throughput

Process planning and scheduling is an important part of managing the complex dynamic back end (i.e., test, assembly, and packaging) of the semiconductor manufacturing process. One of the most critical toolsets in the back end in terms of manufacturing capacity and product flow is the wirebonders that electrically connect bare silicon die to lead frames via thin metal wires. We develop two approaches for maximizing throughput on a group of wirebonders containing three different wirebonder types. Although our mathematical programming approach is capable of producing a near-optimal wirebonder schedule for any production day of interest, the computational requirements of this approach are unacceptable for implementation in a real-world back-end facility. Therefore, we develop a rule-based heuristic approach for wirebonder scheduling capable of producing high-quality schedules in a much shorter period of time.

Observation of explosive spectral behaviors in proton-enhanced high-Q inductors and their explanations

The verified success of proton-beam treatment in both device isolation and inductor Q-improvement on Si substrates is now enticing some big chipmakers into realizing a VLSI back-end facility: the particle-beam stand (PBS). The PBS can potentially end the traditionally laborious mixed-mode product development cycle and eventually become the general system-on-a-chip (SOC) integration platform. However, the observed Q-improvement might in fact fall short of what it should be. Namely, if substrate resistivity is the sole dominant factor deciding the ultimate inductor Q value, then the proton-achieved resistivity does not bring forth the anticipated ideal Q value. Furthermore, there are several puzzles in the observed inductance spectral behaviors. Thus, there is an explosive rise of inductance near certain frequencies in some cases but not in others, and the inductor size effect alters the frequency at which these inductance rises occur. Such difficulties outwit the existing understanding of the microstrip inductors. A new theory is briefly presented here to unravel the cause of such incomplete Q-improvement and hopefully to resolve all related puzzles. It includes identifying the inductor-substrate coupling effect as a result of the proton bombardment, using a special dipole-dominated expansion of the inductor system equations, and further applying the notion of electromagnetic mass of the electron. With such theoretical insight, ideal high-Q passives may be just a few steps away using the so-called "dipole engineering" approach on PBS.