Conference Agenda

In recent years, Sb₂Se₃ has been identified as an ideal phase change material for phase modulation of light because it exhibits no intrinsic absorption losses (k<10^-5) in both amorphous and crystalline phases and an index contrast of ∆n = 0.77 (n_amorph = 3.285 and n_crys = 4.05) over telecommunication transmission band [1]. Also, the crystallization and amorphization temperatures of Sb₂Se₃ are 200ºC and 620ºC, respectively, comparable to those of Ge₂Sb₂Te₅ (GST) which is the most commonly used phase change material (T_crys = 140ºC and T_amorph = 550ºC) [2]. Furthermore, it is known that Sb₂Se₃ supports multilevel operation. The bidirectional multilevel operation of Sb₂Se₃ via a single-step partial crystallization and/or single-step partial amorphization scheme has been realized previously [3-4]. Quasi-continuous multilevel phase modulation has been achieved by controlling the programming energy (e.g., by adjusting the excitation pulse amplitude and width) [3-4] and engineering the temperature profile across the heater [4].

On-chip one-dimensional (1D) metasurfaces provide an innovative means of control over the diffraction and interference of light [5]. In this work, highly adaptive optical routing of guided waves is enabled by on-chip programmable Sb₂Se₃ phase-change metasurfaces. Driven by Genetic algorithm optimizations, a programmable optical router is devised by integrating on-chip 1D metasurfaces [5] with ultralow-loss Sb₂Se₃ on the silicon-on-insulator platform. The on-chip optical routing is achieved by adjusting the refractive index of the Sb₂Se₃ inclusions of the on-chip 1D metasurfaces (that is realizable by partial crystallization of Sb₂Se₃). This is an alternative method for defining the light flow to programmable on-chip cascaded interferometers and photonic meshes, with much smaller footprint and nonvolatile operation.

Fourier optics, besides providing a reasonable model of electromagnetic wave propagation in many applications, presents very computationally-efficient formulations of diffraction by exploiting fast Fourier transforms (FFTs) [6]. This has made Fourier-optics very ideal for incorporating into gradient descent procedures and/or performing real-time optimizations [6]. Our investigations, however, demonstrate that the combination of Fourier-optics with gradient-based optimizations lacks sufficient accuracy for the design and optimization of photonic devices. The combination of a full-wave electromagnetic solver that has the highest degree of accuracy, with gradient-based optimization methods, on the other hand, is restricted by the difficulty in obtaining the gradient information on a physical device [7]. In this article, the Lumerical 2.5D varFDTD solver which accurately and quickly can model the propagation of light in planar integrated optical systems on the scale of hundreds of microns [8] is incorporated into the Genetic algorithm to design the on-chip programmable optical router based on integrated one-dimensional Sb₂Se₃ phase change metasurfaces with the desired input/output routing. The effects of various Genetic algorithm hyper-parameters like partial reinitialization, population size and the number of generations in each optimization are also discussed. Finally, the presented design approach is compared to gradient-based methods combined with Fourier-optics. Supported by our results, the combination of the genetic algorithm with 2.5D FDTD simulations provides a more accurate, yet nearly fast approach to optimize the optical devices, compared to the gradient-based optimization methods relying on Fourier-optics models [9-10].

We describe the design and fabrication of silicon nanowire (SiNW)-based nanosensor devices for detecting explosives compounds. The SiNW-based nanosensor was fabricated using UV-photolithography and electron-beam thermal evaporation. Various parameters and procedures were optimized during the fabrication process. The SiNW was prepared and functionalized with triethoxysilylbutyraldehyde (TESBA) through self-assembly via covalent interactions. After the interaction, sensitivity studies were performed using explosive materials as the target detection molecule. The electrical response and sensing characteristics of the SiNW-based biosensor devices were measured using current-voltage (IV) analysis.

In recent decades, humanity has faced various global challenges that impact all living beings' economies, health, and survival. Pollution and access to soil and the environment are among the five most pressing issues. To tackle these challenges, numerous research groups worldwide have concentrated on developing innovative materials at various scales for detecting hazardous chemicals in soil, air, and water. 4-Nitrophenol (4-NP) is widely used in the pharmaceutical, leather, dye, and agrochemical industries. However, 4-NP is one of the most toxic and hazardous phenolic compounds, capable of causing lasting harm to humans, animals, and plants. It can irritate the skin, eyes, and respiratory system and may also adversely affect the liver and kidneys in humans. The United States Environmental Protection Agency (US EPA) has classified 4-NP as a priority pollutant that must be regulated in soil and the environment due to its significant toxicity; the maximum allowable concentration should remain below 0.43 μM. Additionally, the high stability and low biodegradability of 4-NP make it extremely difficult to remove from the environment. Electrochemical methods and high-performance liquid chromatography are employed to detect trace amounts of 4-NP. These methods are expensive, complex, and not easily accessible. There is increasing interest in developing new analytical tools for detecting 4-NP, underscoring the urgent need for straightforward, affordable, and rapid methods to identify trace levels of these compounds. In this regard, developing simple, reliable SiNW-based biosensor devices for detecting 4-NP addresses this urgent need and potentially significantly impacts environmental monitoring and protection.

The fabricated sensor array was conjugated with TESBA through self-assembly via covalent interaction. The SiNW surface was modified through siloxane (Si-O-Si) linkages, with the hydroxyl group facilitating the conjugation. The anti-TNT was immobilized on the TESBA functionalized SiNW sensor array using covalent interaction with the help of the hydroxyl group. The conjugated sensor array was used for the detection of 4-NP. The sensor array's electrical response and sensing behavior were analyzed using IV (current-voltage) measurement in the presence of 4-NP. Various spectroscopic and microscopic techniques examined the sensor array, functionalization, and sensing characteristics.The prepared SiNW observed an average dimension of 50 nm wide and 13.6 um long. From the analysis, SiNW-based nanosensor array bridged silicon nanowires between the chromium/gold metal layers. The results were compared with microscopic images which indicate that the fabricated sensor array contains no defects.

In recent years, there has been a big progress in artificial intelligence (AI) and high-performance computing (HPC), that have profoundly impacted the semiconductor industry. This progress has driven important innovations in hardware, particularly through the evolution of semiconductor manufacturing nodes, chiplet architectures, advanced packaging (AP), and high-speed interconnects. The continuous pursuit of higher computing power, improved performance, and enhanced system efficiency has boosted AP technolog families—such as Fan-Out, Flip-Chip, and 2.5D/3D —beyond their traditional limitations in form factor, bandwidth, manufacturability, and cost.

A critical challenge in this evolution lies in IC substrates, the foundational layer of advanced packages. The growing demands of AI workloads have directly influenced IC substrate development, necessitating improvements in line/space (L/S) scaling, larger form factors, mechanical stability, and the adoption of novel core materials. Among emerging solutions, glass core substrates (GCS) have gained attention as a promising alternative to conventional organic build-up substrates, offering many advantaghe such as superior dimensional stability, thermal conductivity, and electrical performance. These advantages enable finer interconnects and larger package sizes, which are critical for next-generation AP and HPC applications and can be also important for the Co-Packaged Optics (CPO).

However, the transition to GCS introduces several manufacturing challenges. Key bottlenecks include Through-Glass Via (TGV) fabrication, which requires precise laser drilling and metallization while minimizing defect formation, as well as surface chemistry optimization for reliable copper adhesion. Additionally, challenges related to the coefficient of thermal expansion (CTE) mismatch, warpage, and large-area glass handling must be addressed to enable scalable production. The adoption of GCS also necessitates advancements in panel-level manufacturing equipment to accommodate the unique characteristics of glass substrates.

This paper explores the ongoing efforts by IC substrate manufacturers to meet evolving industry requirements, the emergence of GCS as an emergent technology, and the key bottlenecks that must be overcome for a wider adoption. As glass substrates gain traction, particularly for high-performance AI and HPC applications, their potential to enable next-generation chip-to-chip interconnects and high-density redistribution layers (RDLs) is increasingly evident.