Atomic layer etching can lead to more powerful microchips and supercomputers than ever before

For almost 60 years, the information age has brought the Internet, smartphones, and ultra-fast computers to the world. This is made possible by doubling the number of transistors that can be packed into a computer chip every two years, resulting in billions of atomic-scale transistors that fit into a fingernail-sized device. .. Even individual atoms can be observed and counted within the length of such an “atomic scale”.

Physical limits

When this doubling reaches its physical limits, the US Department of Energy’s (DOE) Princeton Plasma Physics Institute (PPPL) Is participating in the industry’s efforts to extend the process and find new technologies to create more powerful, efficient and cost-effective chips than ever before. In the first PPPL study under a Cooperative Research and Development Agreement (CRADA) with Lam Research Corp., a global producer of chip manufacturing equipment, laboratory scientists used modeling to make atomic-scale chips. Properly predicted the basic stage.

“This is one small part of the whole process,” said David Graves, Deputy Director of Cold Temperature. plasma Surface Interaction, Professor of Chemistry and Biotechnology, Princeton University, Journal of Vacuum Science & Technology B.. The insights gained through modeling “can lead to all sorts of good things, so there is some hope for this effort in the lab.”

Joseph Bella David Graves PPPL

Physicists Joseph Bella (left) and David Graves (paper figure). Credits: Ben Marshall, Photo of Vella; Photo courtesy of Princeton University, Department of Chemistry and Biotechnology.Collage by Kiran Sudarsanan

The contraction can’t last any longer, but “it’s not completely over,” he said. “In the past, the industry has succeeded primarily in using empirical methods to develop innovative new processes, but a deeper, basic understanding speeds up this process. It takes time and requires expertise that the industry does not always have, “he said. “This creates a strong incentive for the institute to take on the job.”

PPPL scientists have modeled what is called “atomic layer etching” (ALE). This is an increasingly important manufacturing step aimed at removing a single atomic layer from the surface at one time. This process can be used to etch complex 3D structures onto films on silicon wafers with marginal dimensions that are thousands of times thinner than human hair.

Basic agreement

“Simulation can basically agree with the experiment as a first step and gain a better understanding of using ALE for atomic-scale etching,” said Joseph Vella, a postdoctoral fellow at PPPL. I am. With a better understanding, PPPL will be able to investigate the degree of surface damage and the degree of roughness that occurs during ALE. “It all starts with building a basic understanding of atomic layer etching,” he said.

This model used chlorine gas and argon plasma ions in sequence to simulate controlling the silicon etching process on an atomic scale. Plasma, or ionized gas, is a mixture of free electrons, positively charged ions, and neutral molecules. In contrast to the ultra-high temperature plasmas used in fusion experiments, the plasma used in the processing of semiconductor devices is close to room temperature.

“A surprising empirical finding from Lam Research was that the ALE process became particularly effective when the ion energy was significantly higher than we started,” Graves said. “This is the next step in the simulation. See if you can understand what is happening when the ion energy is much higher and why it is so good.”

In the future, “the entire semiconductor industry is looking at a significant expansion of the types of materials and devices used, and this expansion also needs to be processed with atomic-scale precision,” he said. “The goal of the United States is to lead the world in using science to tackle important industrial issues, and our job is part of that,” he said.

See: Joseph R. Vella, David Humbird, David B. Graves, “Molecular Dynamics of Silicon Atomic Layer Etching with Colin Gas and Argon Ions”, February 10, 2022, Journal of Vacuum Science & Technology B..
DOI: 10.1116 / 6.0001681

This study was partially supported by the DOE Science Department. Co-authors included David Humbird of DWH Consulting in Centennial, Colorado.

PPPL, Princeton UniversityThe Forestal Campus in Plainsboro, NJ is dedicated to creating new knowledge about plasma physics (ultra-high temperature charged gases) and developing practical solutions for producing fusion energy. Atomic layer etching can lead to more powerful microchips and supercomputers than ever before

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