Manufacturing Bits: June 2

EUV lithography in outer space
The U.S. space program made history on May 31, 2020, when NASA astronauts Robert Behnken and Douglas Hurley aboard SpaceX’s Crew Dragon spacecraft arrived at the International Space Station (ISS). This is the first time a commercial spacecraft has delivered astronauts to the ISS.

The ISS serves as a research lab for companies, government agencies and universities. For some time, astronauts on the ISS have conducted a plethora of innovative experiments at the orbiting lab from various organizations.

For example, the world’s first EUV-based lithography experiment was recently conducted on the ISS, a move that could lay the foundation for advanced chip manufacturing in space.

On Nov. 2, 2019, Northrop Grumman’s Cygnus spacecraft was launched from Wallops Flight Facility in Virginia. The spacecraft carried a payload or experiment from Astrileux to the ISS. The payload was carried out in partnership with the Center for the Advancement of Science in Space (CASIS) and Nanoracks. The spacecraft carried more than 20 other payloads.

NG-12 Mission Rocket Launch, Wallops Island Virginia, Nov 2, 2019 Credit: Dr. Jan Van Schoot

With the payload from Astrileux, astronauts from the ISS last November conducted a lithography experiment on the external platform of the orbiting laboratory. The experiment centered around Astrileux’s new EUV optical coating technology. The goal of the experiment was to determine if it was possible to capture solar EUV radiation using Astrileux’s EUV coatings. These materials form the basis of optics and mirrors for EUV lithography tools at 13.5nm wavelengths.

The experiment proved to be successful. As a result, the materials from Astrileux could one day enable a new class of space instruments. It also lays the foundation for futuristic EUV-based lithography in space, which use the power of solar radiation as the light source.

Nonetheless, originally commissioned in 2000, the ISS is a modular space lab. The ISS is a collaborative effort between space agencies in the U.S., Russia, Japan, Europe and Canada. On the ISS, astronauts conduct scientific experiments in astrobiology, astronomy, meteorology and physics.

Making chips and components is another topic of interest in space. “The goal to extend human life in space beyond 1,000 days is benefitted by an electronics manufacturing ecosystem that supports a localized, self-sustaining community on board the International Space Station,” said Supriya Jaiswal, chief executive at Astrileux. “The capability to rapidly prototype electronics on an as-needed basis by working astronauts creates new functionality and capability on board the ISS, enabling new computing power and performance, the ability to create new smart devices, and rapidly repair obsolete or damaged electronics that might occur in high-risk operations.”

It’s hard to imagine that a full-blown fab with large EUV tools will ever be constructed in the ISS or even on the Moon or Mars. But in the future, it’s conceivable that a small-scale fab or mini-fab could be developed in space.

For this, spacecrafts or space colonies will require 3D printers and fab tools. Lithography is needed to pattern silicon wafers. That’s where the collaboration with Astrileux, CASIS and Nanoracks comes in. CASIS is the manager of ISS’ United States National Laboratory, a U.S. government-funded lab.

Nanoracks, an aerospace company, has installed two research platforms on ISS’ U.S. National Laboratory. Each platform holds up to 16 payloads in a CubeSat form factor, according to Nanoracks. Each CubeSat payload is 4 inches x 4 inches x 4 inches.

For the experiment, Astrileux designed the payload, which was incorporated in Nanorack’s CubeSat. The CubeSat included the internal and external components of Astrileux’s payload.

Last November, ISS astronauts mounted Astrileux’s payload in the airlock, which robotically loaded it onto an external platform. Then, the experiment was activated. Part of the CubeSat was exposed to the Sun. The goal was to capture enough solar radiation using Astrileux’s EUV coatings. The project studied how EUV materials might survive degradation in extreme radiation environments.

In the experiment, Astrileux’s materials successfully performed in the EUV wavelength range (10nm-20nm). “Astrileux created new EUV optical coatings that can survive in an extreme radiation environment and efficiently capture EUV radiation at 13.5nm and other EUV wavelengths,” Jaiswal said.

Given the successful results, these materials could one day be used in several applications. First, it could pave the way towards a new class of space instrumentation that can capture EUV radiation. “Astrileux’s new EUV optics provide the foundation for new designs of optical systems used in space exploration, solar radiation imaging, ground-based telescopes, satellite systems and space systems,” Jaiswal said.

There are other new and future applications as well. “The objective of this experiment was to lay the foundation for electronics manufacturing in space at 7nm and smaller,” Jaiswal said. “The Astrileux payload measures and captures EUV solar radiation at lithography wavelengths of 13.5nm while orbiting the earth. Normally, an EUV lithography tool with a powerful light source is used to pattern wafers at a desired wafer throughput. However, this payload measures and captures natural solar EUV radiation that can be used to pattern a silicon wafer.”

While traditional EUV optics may take more than 100 days to pattern a single wafer, Astrileux’s optics can ultimately reduce the patterning time to less than 10 hours. This in turn makes wafer patterning and manufacturing for a small community in space a viable concept.

What’s next? On earth, meanwhile, several foundries have moved EUV lithography into production at both 7nm and 5nm with 3nm in R&D. Astrileux’s new EUV coatings are also ideal for EUV lithography scanners in production fabs.

Chemistry in space
Separately, in April of 2020, an unmanned version of SpaceX’s Dragon spacecraft splashed down off the coast of California. The spacecraft brought back dozens of research experiments sponsored by ISS’ U.S. National Laboratory.

The spacecraft was originally launched on March 6 and spent 30 days berthed to the space station before returning to Earth.

In one experiment, Space Tango and Boston University developed a platform to support in-orbit chemical reactions. Boston University’s Beeler Research Group was selected by the ISS National Lab to develop reactor systems for flow chemistry applications in space.

The team studied the effects of microgravity on synthetic chemical reactions. This in turn is a step towards the on-demand production of chemicals and materials in space.

Continuous flow technologies facilitate the synthesis and medicinal chemistry of target molecules, according to Beeler Research Group. Flow chemistry enables reactions that have traditionally been challenging to carry out, according to the group.

On the ISS, experiments were conducted in a reactor system, which is an expansion of an existing liquid-liquid separation unit developed by the Beeler Research Group. The chemistries and solvents were enclosed in tubing, enabling safe handling of organic chemicals in space.

Three experiments were conducted. One involved the mixing efficiency of a water-based reaction. Another one involved a biphasic reaction. The third experiment involved more complex synthetic reactions.

“Alongside Space Tango and the ISS National Lab, we have developed a flow chemistry platform that provides the chemistry community a safe approach to studying the effects of microgravity on chemical reactions,” explained Boston University Principal Investigator Aaron Beeler. “These early efforts are critical as we identify the potential influence microgravity has on the synthesis and manufacturing of pharmaceuticals, materials, and biologics. This will also provide a blueprint on how to best implement synthetic chemistry toward humanity’s expansion into space.”

“Installing a ‘Chemical Reactor System’ on the ISS National Lab represents a big step for science and an even bigger one for the chemistry community,” said ISS National Lab Director of Scientific Partnering Kenneth Savin. “For the first time, we will have the ability to take advantage of microgravity’s effects on chemical transformations and the ability to make changes dynamically to the conditions applied to the process.”