# Nanocrystalline diamond-glass platform for the development of three-dimensional micro- and nanodevices

## TL;DR

This paper presents a low-cost, photolithography-free process to create nanocrystalline diamond-glass platforms with through glass vias, enabling advanced 3D micro- and nanodevices for biomedical, electronic, and quantum applications.

## Contribution

It introduces a novel fabrication method for NCD-glass TGVs that simplifies production and enhances potential for diverse 3D device integration.

## Key findings

- Successfully fabricated sealed NCD TGVs with 175 nm thickness and 60 μm diameter.
- Demonstrated potential applications in single-cell analysis, microelectrodes, and quantum technologies.
- Process can be adapted with silicon nitride or silicon carbide for complex heterogenous structures.

## Abstract

Low-cost and robust platforms are key for the development of next-generation 3D micro- and nanodevices. To fabricate such platforms, nanocrystalline diamond (NCD) is a highly appealing material due to its biocompatibility, robustness, and mechanical, electrical, electrochemical, and optical properties, while glass substrates with through vias are ideal interposers for 3D integration due to the excellent properties of glass. However, developing devices that are comprised of NCD films and through glass vias (TGVs) has rarely been attempted due to a lack of effective process strategies. In this work, a low-cost process - free of photolithography and transfer-printing - for fabricating arrays of TGVs that are sealed with suspended portions of an ultra-thin NCD film on one side is presented. These highly transparent structures may serve as a platform for the development of microwells for single-cell culture and analysis, 3D integrated devices such as microelectrodes, and quantum technologies. The process is demonstrated by fabricating TGVs that are sealed with an NCD film of thickness 175 nm and diameter 60 $\mu$m. The technology described can be extended by replacing NCD with silicon nitride or silicon carbide, allowing for the development of complex heterogenous structures on the small scale.