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Crafted from the same element found in sand and covered in intricate patterns, the microchips power smartphones, enhance appliances and help drive cars and airplanes.

Now, scientists at the US Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) are developing computer simulation codes that will outperform current simulation techniques and use plasma to manufacture microchips. will help, the electrically charged state of matter is also used in fusion research. .

These codes could help increase the efficiency of manufacturing processes and potentially spur a renaissance of the chip industry in the United States.

“Because devices with microchips are essential to our daily lives, how and where they are made is a matter of national security,” said Igor Kaganovich, a principal research physicist in the low-temperature modeling group at PPPL. lead the

“Robust and reliable simulation tools that can accurately predict plasma behavior and shorten the manufacturing and design cycle of silicon chips allow the U.S. to regain leadership in this field and maintain it for decades.” can help keep.”

Pick up speed

One PPPL research effort involves reducing the time it takes for computers to simulate microchip plasma reactors. This innovation will help private industry to widely use more complex and accurate replicas and help in their drive to reduce the cost of microchips.

“Companies may want to use simulations to improve their processes, but they are usually computationally expensive,” said Andrew Tasman Powis, Paper Reporting the results Physics of plasma and Computational Research Associate at PPPL. “We are doing our best to counter this trend.”

Physicists typically want to reproduce plasmas as accurately as possible, creating virtual images that show the intricacies of plasma behavior in great detail. This process requires algorithms, programs following a set of rules, that simulate the plasma in a very short time increment and in a small amount of space.

The catch is that such detailed simulations require powerful computers that run for days or weeks at a time. That time frame is too long and too expensive for companies that want to use simulation to improve their microchip manufacturing processes.

The researchers discovered. A history of finding pre-developed algorithms that may be able to reduce the time required to simulate microchip plasmas. Researchers have found suitable algorithms since the 1980s. When tested, the algorithm demonstrated its ability to model a microchip plasma system in much less time and with only a small loss in accuracy.

In essence, the researchers found that they could achieve good simulations despite the modeling. Within larger spaces and using longer time increments

“This advance is important because it can save companies both time and money,” said Haumannson, the study’s lead researcher and a former graduate student in Princeton University’s plasma physics program, based at PPPL. .

“This means that with the same amount of computational resources, you can make more simulations. More simulations not only allow you to find ways to improve manufacturing, but generally learn more physics.” We can make more discoveries using our limited resources.”

Related research led by Powis reinforces this possibility. In a ___ Paper Published in Physics of plasmaPowis confirms that computer code can produce accurate models of plasma particles while using virtual “cells,” or small volumes of space that exceed a standard measurement in plasma physics called the Debye length. .

This development means that the codes can use fewer cells in practice and reduce the computing time required. “This is good news because reducing the number of cells can reduce the computational cost of the simulation and therefore improve performance,” said Poos.

The algorithms can simulate so-called “capacitance-coupled plasma reactors,” which create the plasma that engineers use to draw narrow channels in a wafer of silicon. These tiny pathways form the microcircuitry that allows the microchip to function.

“We are interested in modeling the process so that we can learn how to control the plasma properties, predict what they will be like in a new machine, and then predict the etching properties,” said Powis. So we can improve the process,” said Poos.

The team plans to further test the algorithm by incorporating the effects of different types of wall and electrode materials. “We want to continue to build confidence in these algorithms so that we can be sure that the results are accurate,” Powis said.

Recognizing and overcoming inherent limitations

Another research effort focuses on the errors that can creep into plasma simulations due to the inherent limitations of self-simulation methods, which model the small number of plasma particles present in real plasmas.

“When you simulate a plasma, you ideally want to track each particle and know where it is at all times,” said Sierra Joben, a graduate student in the Princeton Program in Plasma Physics and its lead author. said the author. Paper Reporting the results Physics of plasma. “But we don’t have unlimited computing power, so we can’t do that.”

To solve this problem, the researchers designed code to represent millions of particles as one. giant Particle doing this simplifies the computer’s work, but also increases the interaction of virtual megaparticles. As a result, the change in the ratio of particles moving at one speed versus how many are moving at another—a process known as thermalization—occurs faster than in nature. Basically, simulation doesn’t match reality.

“This is a problem because if we don’t solve this problem, we won’t be modeling the phenomena as they actually happen in the world,” Jobin said. “And if we want to know how many electrons are moving at a particular speed, producing ions or reactive chemical species that interact with the materials used to make the microchips, we need an accurate picture. Won’t get it.”

To compensate for these computational errors, the researchers found that they could make the megaparticle volume larger and less dense, dampening their interactions and reducing changes in the particle’s momentum. “In fact, these results put limits on what is possible in microchip plasma simulations, indicate constraints that we have to consider, and offer some solutions,” Jobin said. Joban said.

Jobin’s results reinforce the notion that existing simulation techniques must be improved. Whether the codes used today require small volume sizes and time increases that simultaneously slow down simulations or because they introduce errors based on computational demands, scientists need new solutions. Is. “It’s actually one. in the field,” Kaganovich said, “and the PPPL is leading the way.”

The team includes researchers from Princeton University, the Swiss Plasma Center of Ecole Polytechnique Fédérale de Lausanne, India’s Birla Institute of Technology and Science, India’s Homi Bhabha National Institute, the University of Alberta in Edmonton, Applied Materials, Inc. and China’s Sino were included. – French Institute of Nuclear Engineering and Technology.

More information:
Serra-Jobin et al., Numerical Thermalization in 2D PIC Simulations: Practical Estimates for Low-Temperature Plasma Simulations, Physics of plasma (2024). DOI: 10.1063/5.0180421

AT Powis et al, Validity of the implicit energy-conserving particle-in-cell method for low-resolution simulations of potential-coupled plasma discharges, Physics of plasma (2024). DOI: 10.1063/5.0174168

Haomin Sun et al, Direct Implicit and Explicit Energy Conserving Particle-In-Cell Methods for Modeling Capacitively Coupled Plasma Devices, Physics of plasma (2023). DOI: 10.1063/5.0160853

Reference: Plasma scientists develop computer programs that could cut cost of microchips, speed up manufacturing (2024, Feb. 21) https://phys.org/news/2024-02 February 21, 2024 Retrieved from -plasma-scientists-microchips.html

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