Algorithms for DFM in electronic design automation

As the dimension of features in integrated circuits (IC) keeps shrinking to fulfill Moore’s law, the manufacturing process has no choice but confronting the limit of physics at the expense of design flexibility. On the other hand, IC designs inevitably becomes more complex to meet the increasing demand of computational power. To close this gap, design for manufacturing (DFM) becomes the key to enable an easy and low-cost IC fabrication. Therefore, efficient electronic design automation (EDA) algorithms must be developed for DFM to address the design constraints and help the designers to better facilitate the manufacture process. As the core of manufacturing ICs, conventional lithography systems (193i) reach their limit for the 22 nm technology node and beyond. Consequently, several advanced lithography techniques are proposed, such as multiple patterning lithography (MPL), extreme ultra-violet lithography (EUV), electron beam (E-beam), and block copolymer directed self-assembly (DSA); however, DFM algorithms are essential for them to achieve better printability of a design. In this dissertation, we focus on analyzing the compatibility of designs and various advanced lithography techniques, and develop efficient algorithms to enable the manufacturing. We first explore E-Beam, one of the promising candidates for IC fabrication beyond the 10 nm technology node. To address its low throughput issue, the character projection technique has been proposed, and its stencil planning can be optimized with an awareness of overlapping characters. 2D stencil planning is proved NP-Hard. With the assumption of standard cells, the 2D problem can be partitioned into 1D row ordering subproblems; however, it is also considered hard, and no efficient optimal solution has been provided so far. We propose a polynomial time optimal algorithm to solve the 1D row ordering problem, which serves as the major subroutine for the entire stencil planning problem. Technical proofs and experimental results verify that our algorithm is efficient and indeed optimal. As the most popular and practical lithography technique, MPL utilizes multiple exposures to print a single layout and thus allows placement of features within the minimum distance. Therefore, a feasible decomposition of the layout is a must to adopt MPL, and it is usually formulated as a graph k-coloring problem, which is computationally difficult for k > 2. We study the k-colorability of rectangular and diagonal grid graphs as induced subgraphs of a rectangular or diagonal grid respectively, since it has direct applications in printing contact/via layouts. It remains an open question on how hard it is to color grid graphs due to their regularity and sparsity. In this dissertation, we conduct a complete analysis of the k-coloring problems on rectangular and diagonal grid graphs, and particularly the NP-completeness of 3-coloring on a diagonal grid graph is proved. In practice, we propose an exact 3-coloring algorithm for those graphs and conduct experiments to verify its performance and effectiveness. Besides, we also develop an efficient algorithm for model based MPL, because it is more expensive but accurate than the rule based decomposition. As one of the alternative lithography techniques, block copolymer directed self-assembly (DSA) is studied. It has emerged as a low-cost, high- throughput option in the pursuit of alternatives to traditional optical lithography. However, issues of defectivity have hampered DSA’s viability for large-scale patterning. Recent studies have shown the copolymer fill level to be a crucial factor in defectivity, as template overfill can result in malformed DSA structures and poor LCDU after etching. For this reason, the use of sub-DSA resolution assist features (SDRAFs) as a method of evening out template density has been demonstrated. In this dissertation, we propose an algorithm to place SDRAFs in random logic contact/via layouts. By adopting this SDRAF placement scheme, we can significantly improve the density unevenness and the resources used are also optimized. We also apply our knowledge in coloring grid graphs to the problem of group-and-coloring in DSA-MPL hybrid lithography. We derive a solution to group-3-coloring and prove the NP-completeness of grouping-2-coloring

Adapting Segment Anything Model for Change Detection in HR Remote Sensing Images

Vision Foundation Models (VFMs) such as the Segment Anything Model (SAM) allow zero-shot or interactive segmentation of visual contents, thus they are quickly applied in a variety of visual scenes. However, their direct use in many Remote Sensing (RS) applications is often unsatisfactory due to the special imaging characteristics of RS images. In this work, we aim to utilize the strong visual recognition capabilities of VFMs to improve the change detection of high-resolution Remote Sensing Images (RSIs). We employ the visual encoder of FastSAM, an efficient variant of the SAM, to extract visual representations in RS scenes. To adapt FastSAM to focus on some specific ground objects in the RS scenes, we propose a convolutional adaptor to aggregate the task-oriented change information. Moreover, to utilize the semantic representations that are inherent to SAM features, we introduce a task-agnostic semantic learning branch to model the semantic latent in bi-temporal RSIs. The resulting method, SAMCD, obtains superior accuracy compared to the SOTA methods and exhibits a sample-efficient learning ability that is comparable to semi-supervised CD methods. To the best of our knowledge, this is the first work that adapts VFMs for the CD of HR RSIs

Hopf bifurcation analysis in a neutral predator-prey model with age structure in prey

We show a detailed study on the dynamics of a neutral delay differential population model with age structure in the prey species. By selecting the mature delay as a bifurcation parameter, we obtain the stability and Hopf bifurcations of the coexistence equilibrium. Moreover, by computing the normal form on the center manifold, we give the formulas determining the stability of periodic solutions and the direction of Hopf bifurcation. Finally, we give some numerical simulations to support and strengthen the theoretical results

Using of Linux Containers in Test Fixture

Táto práca sa zaoberá štúdiom Linuxových kontajnerov a ich aplikáciou na vytvorenie stabilného prostredia pre testovanie softvéru. Programové riešenie problém delí na niekoľko častí. Najprv sa podľa požiadavok používateľa vytvorí konfigurácia, následne sa podľa nej vytvorí kontajner a nakoniec sa tento kontajner spustí spolu s dodanými testami za použitia platformy Docker. Program sám o sebe naplňuje počiatočné požiadavky, avšak jeho funkcionalita nie je zaručená vzhľadom na využitie softvéru tretej strany ako napríklad správcovia balíkov, čo môže spôsobiť neočakávané chyby za behu programu. Hlavným prínosom práce je zaobalenie platformy Docker tak, aby od užívateľa vyžadovala minimálnu, alebo žiadnu znalosť platformy Docker a umožňovala vytvárať kontajnery zjednodušenou formou.The main focus of this thesis is the study of Linux containers and their application in creation of software test fixtures. The program solution divides the problem into several segments. At first, a configurationisset upin accordance with the user’s specification, next a container is created according to given configuration, and in the end,the created container is launched alongside supplied tests while using the Docker platform. The program itself meets initial requirements although its functionality is not guaranteed as a result of usage of third-party software such as package managers, which may cause unexpected runtime errors. Primary asset of the thesis is the wrapping of the Docker platform to the degree, that its user needs minimal, or no knowledge of the platform, and allows them to create containers in a simplified way

Polynomial time optimal algorithm for stencil row planning in e-beam lithography

Electron beam lithography (EBL) is a very promising candidate for integrated circuit (IC) fabrication beyond the 10 nm technology node. To address its throughput issue, the Character Projection (CP) technique has been proposed, and its stencil planning can be optimized with awareness of overlapping characters. However, the top-level 2D stencil planning problem has been proven to be an NP-hard problem. As its most essential step, the 1D row ordering is believed hard as well, and no polynomial time optimal solution has been provided so far. Previous research formulates the problem as the travelling salesman problem, which is NP-hard and solves it by heuristics. In this thesis, we formulate the problem as a matching problem and propose a polynomial time optimal algorithm, which serves as the major subroutine for the entire stencil planning problem. The optimality of the algorithm is proved, and experimental results are also provided to show that our work makes a great improvement in efficiency and correctness to solve the row ordering problem

An Algorithm for Stencil Planning in E-Beam Lithography

Electronic Beam Lithography (EBL) is an emerging nanolithography technology which directly writes the circuit pattern into wafer by e-beam. As an improved EBL technology, character projection (CP) has shorter manufacturing time, because it can complete a complex pattern with one electron shot by placing a stencil with pre-designed characters. On the other hand, the number of predesigned characters is limited by the area constraint of the stencil. In order to reduce the time of manufacture, it is desirable that more characters can be placed in the stencil such that fewer patterns would be written by conventional EBL. Because some blanking area around each character can be shared, we are able to arrange the characters in different orders, providing us with opportunities to reduce the total area occupied by a certain number of characters. In other words, there is an optimization problem: finding an optimal character order with smallest area given a certain blanking area and total stencil area. Previous work has shown that this problem is NP-hard, which means that it is highly unlikely to be solved by an algorithm with polynomial computational complexity. On the other hand, due to the complexity of the design, algorithms have to be executable in polynomial time. In this thesis, we focus on the one-dimensional order of characters which are basically standard cells, and give an algorithm to solve the optimal arrangement in polynomial time.unpublishednot peer reviewedU of I OnlyUndergraduate senior thesis not recommended for open acces