Ultra-low Reflectivity Black Silicon Pupil Masks

The ALD-Enhanced Far-to-Mid IR Camera Coating is fabricated by first applying a conductively loaded epoxy binder ~500 microns thick onto a conductive metal substrate (e.g., Cu, Al). This serves to provide high absorptance and low reflectance at the longest wavelength of interest, as well as to provide a mechanical buffer layer to reduce coating stress. Borosilicate glass microspheres are coated with a thin film metal via ALD, essentially turning the microspheres into resonators. That film is optically thin in the far infrared and approximates a resistive (~200 ohms per square) coating. Light trapped in the borosilicate glass microspheres is reflected back and forth within the glass–at each contact point, the light is attenuated by 50%. A monolayer of thin metal film-coated borosilicate glass microspheres is applied to the epoxy binder and cured, forming a robust mechanical structure that can be grounded to prevent deep dielectric charging by ionizing radiation in space. Once cured, the far-to-mid IR absorber structure can be coated with a traditional ~20-to-50 microns “black” absorptive paint to enhance the absorption band at short wavelengths, or a “white” diffusive paint to reject optical radiation. At this thickness and broad tolerance, the longwave response of the coating is preserved. Tailoring the electromagnetic properties of the coating layers and geometry enables realization of a broad band absorption response where the mass required per unit area has been minimized. While NASA originally developed the ALD-Enhanced Far-to-Mid IR Camera Coating for the Stratospheric Observatory for Infrared Astronomy mission, its robustness, absorptive qualities, and optical performance make it a significant addition to IR and terahertz imaging systems. The IR camera coating is at Technology Readiness Level (TRL) 3 (experimental proof-of-concept) and is available for patent licensing.

This innovation represents an alternative method to skip several of the conventional fabrication steps, using a mask designed to allow molecules in a sputtering plume to pass through openings engineered in the mask. This causes material to go where desired, without photoresist, and without selective etching, thus simplifying the process, reducing cost, chemical waste; and increasing throughput. This method masks areas that do not need deposited material, causing local deposition instead. The shape and size are within tolerance. No etching steps, no photoresist patterning, and no metal removal is necessary. Other than planarization, selective deposition has replaced every step in the conventional process, accomplishing the same result in 8 steps instead of 19. The technology can be easily used to fabricate custom chips and specialized sensors and devices that use the group III-V and II - VI semiconductor materials.

This invention provides a method and system for fabricating a biomarker sensor array by dispensing one or more entities using a precisely positioned, electrically biased nanoprobe immersed in a buffered fluid over a transparent substrate. Fine patterning of the substrate can be achieved by positioning and selectively biasing the probe in a particular region, changing the pH in a sharp, localized volume of fluid less than 100 nm in diameter, resulting in a selective processing of that region. One example of the implementation of this technique is related to Dip-Pen Nanolithography (DPN), where an Atomic Force Microscope probe can be used as a pen to write protein and DNA Aptamer inks on a transparent substrate functionalized with silane-based self-assembled monolayers. But it would be recognized that the invention has a much broader range of applicability. For example, the invention can be applied to formation of patterns using biological materials, chemical materials, metals, polymers, semiconductors, small molecules, organic and inorganic thins films, or any combination of these.

This NASA invention is an innovative process for fabricating high-area binary phase photon sieves with improved optical efficiency for EUV imaging applications. Binary phase photon sieves have been demonstrated for a variety of optical and x-ray applications. Photon sieves must be wide, super-thin, and etched with precise holes to refract light. Each step in NASA's photon sieve fabrication process includes considerations to protect the resulting sieves, such as leaving a honeycomb of thicker material to support the membrane and prevent tearing. The process starts by using a silicon-on-insulator wafer, includes pattern and etch-sieve pattern, and ends with a released photon sieve. The inventors have produced an 8 cm-diameter silicon sieve that is 100 nm thick including hole sizes of 2 µm in diameter with 2 µm spacing. Additionally, a similar structure has been demonstrated in niobium, with 8 cm in diameter with the same silicon hexagonal support frame. This novel process enables the fabrication of photon sieves for EUV imaging applications. While the process was initially developed to fabricate photon sieves for solar science and astronomy, it could also be used to generate metamaterial/frequency selective surface structures from the UV to THz frequency ranges. This NASA invention is a Technology Readiness Level (TRL) 4 (prototype validation in a laboratory environment) technology and is available for patent licensing.

The Phononic Isolated KID Fabrication Process utilizes a silicon on insulator, or a silicon wafer coated with a thin film bilayer of silicon oxide and silicon nitride (or amorphous silicon), to be used as the starting wafer. The silicon or silicon nitride thin films act as the structural material. The films thicknesses are chosen based on the desirable phononic crystal properties. The phononic crystal is patterned with electron beam lithography to get minimum features. The structures are etched in a fluorine plasma chemistry stopping on the oxide layer. The niobium or other superconductor layer is deposited, patterned, and etched. This can be done in a liftoff process so as not to damage the SiN or Si underlayer. A hafnium or other superconductor is deposited, patterned, and etched to function as the kinetic inductance material. A silicon handle wafer is patterned and etched using deep reactive ion etching which stops on the silicon oxide. The silicon oxide is etched in hydroflouric acid and a wax bonding material used as a temporary bonding material is dissolved. The final structure is removed from the temporary handle wafer. This process is beneficial in that it is simple aside from the incorporation of the nanostructured membranes. The Phononic Isolated KID Fabrication Process is an implementation of incorporation of a phononic crystal into a KID architecture. The process can also incorporate a second dieletric material such as nanocrystalline diamond that can be used as a stiffening material for the phononic crystal.