Orbital Microfabrication

Fabricating microchips and semiconductor crystals in microgravity to benefit from the different physical behaviors, ultra-high vacuum, and other advantages. Microgravity-grown crystals have increased crystal size and suppressed impurities and defects.⁴

Updated: 2024-03-10

Created: 2018-12-07

As of 2023, this field is strongly re-emerging.

In October 2022, Butler University published a study and databases on crystals grown in microgravity.

In March 2023, "The Workshop on Semiconductor Manufacturing in the Space Domain" was held at Stanford.

In November 2023, a white paper was published: Frick, J., Kulu, E., Rodrigue, G., Hill, C., & Senesky, D. (2023, November 8). Semiconductor Manufacturing in Low-Earth Orbit for Terrestrial Use. Retrieved from osf.io/d6ar4.

Terrestrial microfabrication techniques are difficult to transfer into microgravity. New methods have been and are being developed and some have been tested on a small-scale in space.

Microgravity Research Associates was founded in 1979 to produce gallium arsenide chips. Made in Space was selected by NASA in 2020 to develop autonomous semiconductor chip manufacturing.

• Semiconductors
• Gallium Nitride (GaN)
• Gallium Nitride on diamond (GaN-on-diamond)
• Gallium Arsenide (GaAs)
• Silicon Carbide (SiC)
• Space-based microsensors
• Solar cells
• Radiation detectors

Semiconductor microchips are high value per mass products whose fabrication requires many of the resources available in low-Earth orbit. It is hypothesized that orbital fabrication of silicon microchip devices may be more economically attractive than traditional Earth-based fabrication based upon the inherent advantages of the space environment: vacuum, cleanliness, and microgravity.³

Gallium nitride, used to make LEDs, is difficult to solidify in large amounts at a time because its two constituent molecules don't always bind perfectly in order, leading to defects. Reducing the movement of the melted fluid as hotter and less-dense fluid rises, which occurs because of gravity, can decrease those defects — as can preventing the highly reactive substance from touching the sides of its container, according to Randy Giles, chief scientist at the Center for the Advancement of Science in Space. Someday, substances like that could benefit from in-space creation.²

Using orbital vacuum for enhanced semiconductor fabrication was pioneered in the Wake Shield project which produced ultra-high vacuums for epitaxial growth of high quality GaAs like materials. A proposed alternative uses the native Low Earth Orbit vacuum levels to achieve the silicon microfabrication processes needed for manufacturing silicon microchips. However standard terrestrial fabrication techniques are difficult to transfer into the microgravity and vacuum environment of space.  They are optimized for using in-situ resources: water, power, air pressure and gravity that are plentiful on Earth.  An alternative microfabrication process has been developed using the native vacuum environment which could replace wet terrestrial based microfabrication, with significant savings in equipment size, mass and consumables, while reducing cycle time.³

It is found that by developing new, dry processes that are vacuum compatible, fabricating semiconductor devices in orbit is both technically and economically feasible.  The outcome is a synergistic, orbital-based methodology for micro-fabrication capable of building and delivering commercially marketable microfabricated structures.  The base case modeled, production of 5,000 ASIC wafers per month, indicates that orbital fabrication is 103% more expensive than existing commercial facilities.  However, optimization of process parameters and consumable requirements is shown to decrease the cost of orbital fabrication dramatically.  Modeling indicates that the cost of orbital fabrication can be decreased to 58% that of an advanced, future Earth-based facility when trends of increasing process equipment costs and decreasing orbital transport costs are considered.³

Taking advantages of microgravity environment, amorphous semiconductors made a remarkable improvement both in quality and quantity. Space is considered to be a favorable environment for many things including the followings that were investigated: semiconductor joining by atomic adhesion, fabrication of thin films of diamond and amorphous silicon alloys, CVD processes, production of super-minute grains, light element analysis by SIMS (Secondary Ion Mass Spectrometry), and anti-proton generation by laser accelerators. This report reviews the potentials of material processing in space. Processing technologies of spacecraft construction materials, thin solid films, and fine alloys are reviewed. Light element analyzing method and antiproton storing technology for liquid metal MHD (Magnetohydrodynamic) power generator are also reviewed.⁵

Made in Space was selected to develop an autonomous, high throughput manufacturing capability for production of high quality, lower cost semiconductor chips at a rapid rate. Terrestrial semiconductor chip production suffers from the impacts of convection and sedimentation in the manufacturing process. Fabricating in microgravity is expected to reduce the number of gravity-induced defects, resulting in more usable chips per wafer. Market applications include semiconductor supply chains for telecommunications and energy industries. 

Butler University published "An Analysis of Publicly Available Microgravity Crystallization Data: Emergent Themes Across Crystal Types" in 2022 and continues to update the publicly available survey data.

Semiconductor Manufacturing in the Space Domain Workshop, 2023

Industry leaders gathered at Stanford University in March 2023 at the inaugural Semiconductor Manufacturing in the Space Domain Workshop to discuss the past, present, and future of the field.

• This workshop brought together a community of experts to explore the rich history of semiconductor and in-space manufacturing. These experts and their foundational research and collaboration are the driving force behind this paper. The workshop’s priority was to identify the 2030 goals that must be reached to make in-space semiconductor production a reality by 2050.
• The consensus was that the field needs to take the remaining years to de- risk investment from semiconductor corporations and private investors. To do that, the community needs to obtain more iterative data on promising semiconductor R&D in LEO. This would include the whole range of experiments in the semiconductor production phases such as crystal growth, wafer processing, epitaxial growth, circuit patterning, etc. Beyond synthesizing the takeaways from the workshop, the report describes the current state of semiconductor manufacturing in space and carves out a path for the future.
• Over the past three decades, the deteriorating discovery and growth of crystalline materials (DGCM) capacity in the United States has significantly stalled the domestic semiconductor industry. This report intends to regain U.S. attention to space-based semiconductor manufacturing and bring the field back from hibernation. The Vision for 2050 and Call to Action sections, informed by both industry and history experts, propose actionable solutions that can awaken the semiconductor industry from nearly 25 years of inactivity in space.
• The benefits of semiconductor manufacturing in LEO are clear. Earth’s gravitational forces pose substantial barriers to quick, high-yield semiconductor production. Beyond the scientific benefits of microgravity, there are substantial practical benefits to incorporating LEO-based manufacturing into the supply chain. Transitioning this industry into space is the only path forward if the US is to keep pace with the technological arms race unfolding across the globe.
• This report identifies opportunities to strengthen U.S. leadership in the LEO-based semiconductor manufacturing field. The industry urgently needs a roadmap for both immediate and long-term funding strategies that can support various components. Long- term government investments can help de-risk additional private investments, and funding student fellowship programs will drive workforce development.
• Beyond a need for funding, the industry needs a designated collaborative community ecosystem. This field is currently situated alongside several related fields, and gaining traction in established fields is certainly necessary. However, there is a clear need for a designated “home” and community that can draw on knowledge from academia, the space sector, and the semiconductor industry. A push towards this collaborative environment will only benefit the industry at large and give the United States a competitive edge in this growing field.
• This paper will explain the scientific basis for this industry in the proceeding sections. Discussions of the past and present of semiconductor manufacturing in LEO will provide the necessary context for the various author recommendations to develop the industry.

Exists, because lots of research is happening to keep up with the Moore's law and economies-of-scale likely favor Earth in the near-term.