NEXG-UV · Towards next Generation UV Optical Waveguides

Towards next Generation UV Optical Waveguides

The NEXG-UV project addresses the challenge of integrating ultraviolet (UV) light into photonic systems. Integrated photonics, which involves the miniaturization of optical components like lasers, modulators, and detectors onto a single chip, has advanced in visible and infrared wavelengths. However, UV photonics remains underdeveloped due to material limitations. Conventional materials like silicon and silicon nitride (SiN), widely used in infrared and visible photonics, exhibit high absorption at shorter UV wavelengths, making them unsuitable for UV-based applications. This gap in technology limits the potential of UV photonics in fields such as biosensing, quantum computing, and advanced communications. UV photonics has significant societal implications. UV light is essential for highly sensitive biosensing applications, enabling precise detection of biological molecules for medical diagnostics, and other critical uses. In quantum computing, UV photons are vital for manipulating qubits and advancing computation technologies that promise unprecedented processing power. Therefore, advancing UV photonic technology can lead to breakthroughs in healthcare, computing, and communications infrastructure, driving societal progress in critical areas. Throughout the project’s timeline, most objectives and goals across the various work packages (WPs) were successfully achieved. The overall objective of the NEXG-UV project was to develop low-loss photonic waveguides for UV light on a miniaturized chip. This required the identification and integration of materials that could operate efficiently in the UV spectrum. The project explored two key strategies to achieve this: Inverse Damascene Process: This method aimed to fabricate waveguides without direct etching of the material, avoiding sidewall roughness and reducing power losses, which are common in conventional etching processes. Conventional Direct Etching: Utilizing established CMOS foundry techniques, this approach leveraged mature technologies used for silicon nitride (SiN) and silicon platforms, focusing on direct etching to create waveguides. A key material identified was Aluminum Oxide (AlOx), a dielectric with a large bandgap and compatibility with CMOS fabrication. AlOx was chosen for its potential to function efficiently in the UV range, making it an attractive candidate for the development of UV photonic devices. By the project's conclusion, ultra-low-loss waveguides at UV wavelength were successfully fabricated in a CMOS foundry, marking significant progress in UV photonics and bringing the technology closer to commercial viability and widespread societal impact. The following key project objectives and milestones were successfully addressed: • Successful ALD deposition of high-quality AlOx thin films. • Optimization of AlOx thin films for low-loss performance. • Development of an inverse damascene process for AlOx waveguides. • Exploration of thermal SiO2 etching techniques. • CMP process development for AlOx waveguide. • Creation of a PDK for AlOx-based passive elements. • Completion of wafer-scale processing in imec’s 200mm p-line.

Data: CORDIS, © European Union