Energy-Efficient and Environmentally Sustainable Computing Systems Leveraging Three-Dimensional Integrated Circuits

Friday, February 7, 2025 11am to 12pm

150 Western Avenue, Allston, MA 02134

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Friday, February 7
11am - 12pm
SEC LL2.221


"Energy-Efficient and Environmentally Sustainable Computing Systems Leveraging Three-Dimensional Integrated Circuits"


Gage Hills, Harvard University

Abstract

The world’s insatiable demand for computing is having a global impact. In particular, the growing energy requirements of Artificial Intelligence are severely outpacing energy efficiency improvements in today’s computing systems. This unsustainable growth poses threats to our environment. How can we improve computing to address these global needs?

In this talk, I will focus on two outstanding challenges in computing: (1) The well-known memory wall or communication wall. Data communication is a major energy efficiency bottleneck for today’s datacenter-scale distributed computing systems, which comprise hundreds of thousands of interconnected chips for processing and memory. (2) Computing’s carbon footprint challenge. Importantly, computing’s carbon footprint includes both embodied carbon – due to physical manufacturing of computing systems – and operational carbon, from day-to-day use.

I will describe my group’s three-pronged approach to overcome these challenges. Our approach is centered around developing three-dimensional integrated circuits (3D ICs) that combine emerging nanomaterials, compute/memory devices, circuit topologies, computer architectures, and 3D integration techniques. I will start by presenting a 3D IC design of embedded (on-chip) Dynamic Random-Access Memory (DRAM), which we developed to address the memory wall. Second, I will describe a new method we developed for quantifying the embodied carbon footprint of 3D ICs. This is essential for guiding directions in sustainable computing. Finally, I will briefly touch on directions we are pursuing in 3D Electronic-Photonic ICs (EPICs), which combine electronic circuits for high-performance computation, and photonic circuits for high-performance communication. 3D EPICs are also promising to address the communication wall. 

My group’s collective expertise spans multiple layers of the computing stack, which enables us to find cross-cutting solutions that address global challenges in computing. Such grand challenges require massively coordinated efforts, and I will highlight multiple collaborations with our colleagues in Harvard SEAS.


Speaker bio:

Gage Hills is in his 4th year as an assistant professor in Electrical Engineering at Harvard SEAS. He leads the Nano-Design Research Group: https://nanodesign.seas.harvard.edu/, focused on developing future generations of energy-efficient and environmentally sustainable computing systems. His group’s approach is to combine recent technology advances across the computing stack, spanning emerging nanomaterials, compute/memory devices, circuit topologies, computer architectures, and three-dimensional integration techniques. 

As a recent research highlight, his group’s paper: “Quantifying Trade-Offs in Power, Performance, Area, and Total Carbon Footprint of Future Three-Dimensional Integrated Computing Systems” received a Best Paper Award nomination at the Design, Automation, and Test in Europe (DATE) conference in 2025. Twelve papersout of 1,214 were nominated (top <1%). Four winners will be selected at the award ceremony on April 1st in Lyon, France. 

For fundraising, Gage is thankful to have received the NSF CAREER Award, the NSF Expeditions in Computing Award, the NSF EAGER Award, gift funding from Intel Labs, two awards from the Harvard Dean’s Competitive Fund for Promising Scholarship, and Seed Funding from The Salata Institute for Climate and Sustainability.

Gage is also passionate about teaching, advising, and mentoring. He teaches three courses focusing on electronic circuits and related areas: ES 152, CS 148/248, and ES 255. In 2024, he was selected one of three professors across Harvard to receive the Harvard Phi Beta Kappa (PBK) Alpha-Iota Prize for Excellence in Teaching. Among the full list of recipients since 1981, he is the only professor in Electrical Engineering ever to receive this prize. Four of his ES 100 advisees have won Dean’s awards. He is incredibly proud to advise seven outstanding PhD students.

Gage is also dedicated to university service and citizenship. He has served on multiple committees at Harvard, including the SEAS Committee for Diversity, Inclusion, and Belonging, the Graduate Admissions Diversity Subcommittee, two faculty search committees, the HQI post-doc selection committee, the Committee on Higher Degrees, the Climate & Sustainability Working Group, and the Climate / Energy Ad hoc Committee exploring new avenues to integrate Climate Technology into Harvard’s curricula.