New process for printing transparent quartz glass at lower temperatures

The utilization of pure silicon dioxide in the production of micro- and nanometer-scaled quartz glass structures offers exciting possibilities in optics, photonics, and semiconductor technologies. However, traditional methods relying on conventional sintering have imposed limitations.

Conventional sintering techniques involve subjecting silicon dioxide nanoparticles to temperatures exceeding 1100°C. Unfortunately, these high temperatures make it impractical for direct deposition onto semiconducting chips. In light of this challenge, a team led by Dr. Jens Bauer from KIT’s Institute of Nanotechnology (INT) has devised an innovative approach. This novel process enables the fabrication of transparent quartz glass with exceptional mechanical properties and high resolution, all while operating at significantly lower temperatures.

Hybrid organic-inorganic polymer resin as feedstock

Dr. Jens Bauer, who leads the Emmy Noether Junior Research Group “Nanoarchitected Metamaterials” at KIT, along with collaborators from the University of California, Irvine, and Edwards Lifesciences in Irvine, have published their findings on a groundbreaking process in the journal Science.

Their approach involves the utilization of a hybrid organic-inorganic polymer resin as the primary material for their printing technique. This liquid resin contains polyhedral oligomeric silsesquioxane (POSS) molecules, which are small silicon dioxide cages with organic functional groups attached.

By employing 3D printing and subsequently cross-linking the resin, a nanostructure with a three-dimensional architecture is formed. The structure is then subjected to a temperature of 650°C in the presence of air to eliminate the organic components. Simultaneously, the inorganic POSS cages come together and create a continuous microstructure or nanostructure of quartz glass. Remarkably, this temperature requirement is only half of what is typically needed in processes relying on nanoparticle sintering.

Structures remain stable even under challenging chemical and thermal conditions

Dr. Bauer emphasizes, “The reduced temperature requirement now allows for the precise printing of durable, high-quality glass structures suitable for visible-light nanophotonics directly onto semiconductor chips.” The printed quartz glass not only exhibits exceptional optical properties but also boasts excellent mechanical characteristics and can be easily processed.

The team from Karlsruhe and Irvine utilized the POSS resin to successfully print a variety of nanostructures. These included free-standing photonic crystals composed of 97 nm wide beams, parabolic microlenses, and a multi-lens micro objective featuring nanostructured elements. Bauer highlights, “Our process yields structurally robust designs capable of withstanding challenging chemical and thermal conditions.”

Source: Karlsruhe Institute of Technology

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