Director’s Corner
Greetings! Welcome to the quarterly newsletter from the 3D Systems Packaging Research Center (PRC).
A recent report from McKinsey and Company projects the global semiconductor industry to become a trillion-dollar industry by 2030. An interesting observation is that it took the industry 55 years to become a 0.5T dollar industry while in the next ten years this will double in size to become a 1T dollar industry. Heterogeneous Integration (HI) using Advanced Packaging we believe will be a key enabler to make this happen.
Georgia Tech PRC is the largest academic center focused on advanced packaging around the globe. We currently collaborate with 43 companies and 14 universities with more than 60 students involved in leading edge advanced packaging research.
We recently launched our first Advisory Board consisting of six visionaries in advanced packaging. The inaugural members are Prof. Rao Tummala (GT Emeritus Professor and former Director PRC), Dr. Ravi Mahajan (Intel), Dr. Andrew Ketterson (Qorvo), Dr. Doug Yu (TSMC), Dr. Omkaram Nalamasu (Applied Materials), and Dr. Shekhar Chandrashekhar (iNEMI).
To learn more about PRC, please visit us at www.prc.gatech.edu and also do follow us on LinkedIn.
We provide below some recent research highlights.
Sincerely,
Madhavan Swaminathan
Research Highlights
RESEARCH PAPER WINS THE EMC BEST TRANSACTIONS PAPER AWARD
The paper titled “Worst-Case Eye Analysis of High-Speed Channels Based on Bayesian Optimization” is being recognized with the Richard B. Shultz Best Transaction Paper award by the IEEE Electromagnetics Society (EMC) on Aug. 4, 2022. This paper was selected from 242 papers published in the 2021 IEEE T-EMC through a rigorous review and consideration of the editorial board. The authors of the paper are: Majid Ahadi Dolatsara, Jose Ale Hejase, Wiren Dale Becker, Jinwoo Kim, Sung Kyu Lim, and Madhavan Swaminathan. In this article, an optimization-based approach is proposed to quickly obtain the worst-case eye diagram characteristics for chip to chip signaling. To address complexity, the method combines a mapping algorithm that exploits the Gray code with Bayesian optimization. Numerical results show that the proposed approach can accurately find the eye width (EW) and eye height (EH) with up to 47X speedup, and the worst-case eye opening with up to 23X speedup, when compared with the transient eye. Read here.
Three interconnect channel with drivers/receivers (left), eye diagram specifications (EH, EW) (middle), and Worst case eye (right)
ADHESION OF POLYMER-COPPER REDISTRIBUTION LAYERS
The ever-increasing demand for high-bandwidth interconnects has given rise to the need for high IO-density package redistribution layers (RDL). This necessitates scaling down RDL critical dimensions. There are numerous challenges pertaining to the further miniaturization of polymer RDL. The main challenge is the adhesion reliability of copper RDL to the polymer dielectric. Although the 90⁰ peel test is the industry standard, with the latest advances in low K dielectrics and L/S moving towards less than 2um, it is critical to understand the interfacial interactions between dielectrics and copper. The chemical interactions between polymer and metal seed layer play an important role in adhesion reliability. In the paper, by Nimbalkar et al., published in the IEEE Transactions On Device And Materials Reliability, we present a study of chemical interactions between titanium and various commercial polymer dielectrics using XPS and FTIR spectroscopy to enable improved adhesion between polymer and copper. Read here.
Adhesion strength for Ar and Ar-O2-bake processes for different dielectrics (left), FT-IR spectra of pristine, Ar treated and Ar-O2-Bake treated ABF dielectric in 1300-1800 cm-1 (middle), and Infrared spectra of pristine, Ar treated and Ar-O2-bake treated ABF dielectric in 2700-3100 cm-1 (right)
HYBRID ACTIVE-PASSIVE BEAN FORMING FOR SCALABLE SUB-TERAHERTZ ANTENNA ARRAY
Moving from 5G towards next-generation (6G) wireless communications, expanding to new spectrum bands into sub-terahertz (sub-THz) frequencies above 100 GHz becomes necessary for supporting high data rates. As the frequency increases into sub-THz, the path loss becomes much larger, and the atmospheric impact becomes higher. Hence massive multiple-input multiple-output communication with hundreds of antenna elements in an array that provides highly directional radiation beam patterns becomes necessary. In the paper by Kai-Qi Huang et al., presented at the IEEE Symposium on Antennas and Propagation, we discuss a hybrid active-passive beamforming method using a combination of active and passive beam formers. This hybrid beamforming approach represents a scalable array, that minimizes power loss. Read here.
4×4 Sub-array with Butler Matrix, Power Amplifier (PA), and Active Beamformer (left) and 2D Beamforming using cascaded sub-arrays.
Faculty Highlight
Sung Kyu Lim Congratulations to Prof. Sung Kyu Lim for being appointed as the Motorola Solutions Foundation Professor in design automation. Sung-Kyu joined ECE as an assistant professor in 2001, and is currently the director of the GTCAD (Georgia Tech Computer Aided Design) Laboratory with main research focus areas on the architecture, circuit design, and physical design for three-dimensional integrated circuits (3D IC) — a three-dimensional IC built by vertically stacking different chips or wafers together into a single package. His academic research group is the largest in the world working on modeling, design, and electronic design automation (EDA) research for 3D ICs. In 2011 he fabricated the first many-core general purpose 3D processor developed in academia. Sung-Kyu received the Qualcomm Faculty Award in 2017 and 2018 and has frequently been recognized for his teaching at Tech, receiving the Class of 1940 Course Survey Teaching Effectiveness Award in 2016, 2018, 2019 and 2020. In 2020 he was also honored with the Center for Teaching and Learning (CTL) Student Recognition of Excellence in Teaching: Class of 1934 Award for his teaching of ECE 6133: Physical Design Automation of VLSI Systems.
Student SPOTLIGHT
Pratik Nimbalkar is pursuing a Ph.D. in Materials Science and Engineering at 3D Systems Packaging Research Center. He is advised by Prof. Rao Tummala. He is currently developing materials and processes for 1µm RDL technology and also studying its reliability aspects. His research interests include- glass panel packaging, system integration technologies and novel materials & processes in electronics. Prior to starting his Ph.D. at Georgia Tech, he worked at the Center for Materials for Electronics Technology (CMET) and National Chemical Laboratory (NCL), India. He completed his bachelor’s degree in Materials Science and Metallurgy from College of Engineering, Pune, India.
Ethan Shackelford, a PRC undergraduate student in Materials Science and Engineering supported through SCALE has been awarded the Best Poster Paper Award at the TMS, 2022 conference held in Anaheim, CA. His poster was titled “Thermomechanical Clamp for Curing Low-k Dielectric Dry Films” presented his undergraduate research on the design, modeling, fabrication of thermomechanical clamp for use in the curing of low-k dry films to improve the adhesion strength of the films (GRA Mentor: Pragna Bhaskar). Congratulations to Ethan.
Upcoming and Recent Events
PRC Industry Advisory Board meeting November 17th and 18th, 2022 (by invitation only).