South Pole Telescope: Using Maskless Lithography for Ultra-Sensitive Camera

Heidelberg, Germany, 25 June 2018: Researchers from the University of Chicago, Argonne National Laboratory and over a dozen institutions from around the world have been working diligently to develop a new, highly sensitive camera for the South Pole Telescope (SPT) at the National Science Foundation’s South Pole Research Center in Antarctica.files/heidelberg/images/news/South_Pole Jason_Gallicchio.png

This is the third camera upgrade for the largest telescope on the southernmost continent. It gives scientists hope to solve one of physics biggest mysteries: the origin of the universe.

The SPT is a large millimeter-wavelength telescope measuring 33 feet in diameter. It was first completed in 2007 and is designed to detect and measure signals of the Cosmic Microwave Background (CMB). These signals are remnants of the Big Bang that kicked off the universe over 14 billion years ago.

The recent upgrade enables the third-generation camera to carry an array of over 16,000 superconducting detectors, or 10 times the number of detectors on previous versions, increasing the sensitivity ten-fold. Each device requires the deposition of ultra-thin superconducting materials with features as small as about 1 μm.

files/heidelberg/images/news/DetectorArrayCool2.pngThese detectors were fabricated at the Argonne National Laboratory in Argonne, Illinois, using maskless lithography equipment supplied by Heidelberg Instruments. The laboratory installed the MLA150 at its Center for Nanoscale Materials (CNM) as an addition to their existing suite of lithography tools. The new generation maskless aligner is a contact-free technology and features high accuracy with fast exposure speeds at very low running costs.

“The MLA was used to fabricate the Nb leads, which appear as bands in between the pixels” says Clarence Chang, who leads the design and fabrication of the detectors at Argonne. Each pixel consists of a superconducting antenna, which is connected to six superconducting detectors that will be integrated into the focal plane for the camera. With this, the camera is ten times faster than its predecessor. The increased speed facilitates a more accurate mapping of the early universe, which will lead to a better understanding of its beginning. “Prior to the MLA, we were using a contact aligner. We repeat the leads process on many wafers, so the extra cleanliness relative to contact aligner was important.”

The CNM is a premier user facility for interdisciplinary nanoscience and nanotechnology research, so it was important to have a tool that would have the quality, speed and ability to expose patterns with high accuracy. The MLA150 is designed to be a direct alternative to a mask aligner and can expose patterns directly without fabricating a mask, which results in significantly shorter prototyping cycles. This makes it very attractive for research and development and was a major reason for CNM to purchase such a tool. “The flexibility of the MLA is especially helpful in the R&D environment where flexibility and adaptability are invaluable.” says Clarence Chang. “We continue to use the MLA for patterning of trial devices which we use to investigate new ideas and study new problems.”

About Amundsen-Scott South Pole Station:

Located at the South Pole in Antartica, the Amundsen-Scott South Pole Station is a scientific research station with focus on climate, astrophysics and atmospheric composition. Built by the U.S. government in 1956, the most recently updated station today is equipped with more advanced technology and capable of hosting 150 researchers and support staff from around the globe.

About CNM at Argonne National Laboratory:

The Center for Nanoscale Materials (CNM) is premier user facility sponsored by the U.S. Department of Energy. Located at Argonne National Laboratory, the CNM provides academia and industry access to advanced instrumentation and infrastructure for interdisciplinary nanoscience and nanotechnology research.

About Heidelberg Instruments:  With an installation base of over 800 systems in more than 52 countries, Heidelberg Instruments Mikrotechnik GmbH is a world leader in production of high-precision maskless lithography systems.  Due to their flexibility, these systems are used in research, development and industrial applications for direct writing and photomask production by some of the most prestigious universities and industry leaders in the areas of MEMS, BioMEMS, Nano Technology, ASICS, TFT, Plasma Displays, Micro Optics, and many other related applications.


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