As a leading provider of sensing solutions ams AG is developing semiconductor sensors in a wide variety of fields. One of the key competences of ams AG lies in optical sensing. To widen the company’s portfolio in this field we have been developing processes for fully integrated CMOS compatible photonic components based on Si₃N₄ in the last few years. This contribution will give an overview of the Si₃N₄ process as a post-processing flow for standard CMOS, some basic photonic building blocks and their properties, and an example for their use in the field of medical applications.

Metal oxide multi-nanowire-based chemical gas sensors were manufactured by a fast and simple transfer printing technology. A two-step method employing spray pyrolysis deposition and a thermal annealing process was used for SnO ${}_2$ nanowires fabrication. A polydimethylsiloxane stamp was used to transfer the SnO ${}_2$ nanowires on two different gas sensing devices—Si-based substrates and microhotplate-based platform chips. Both contained a metallic inter-digital electrode structure (IDES), on which the SnO ${}_2$ nanowires were transferred for realization of multi-NW gas sensor devices. The gas sensor devices show a very high response towards H ${}_2$ S down to the 10 ppb range. Furthermore, a good response towards CO has been achieved, where in particular the microhotplate-based devices exhibit almost no cross sensitivity to humidity.

A worldwide unique CMOS based chemical sensor device comprising an array of 8 microhotplates (µhps) for a total of 16 chemical sensors has been fabricated (Figure 1).

Photonics integrated circuits (PICs) represent a promising technology for the much-needed medical devices of today. Their primary advantage lies in their ability to integrate multiple functions onto a single chip, thereby reducing the complexity, size, maintenance requirements, and costs. When applied to optical coherence tomography (OCT), the leading tool for state-of-the-art ophthalmic diagnosis, PICs have the potential to increase accessibility, especially in scenarios, where size, weight, or costs are limiting factors. In this paper, we introduce an unprecedented fully integrated CMOS-compatible spectrometer, an optoelectronic system based on PIC for spectral domain OCT. To achieve this, we co-integrated a 512-channel arrayed waveguide grating with electronics. We successfully addressed the challenge of establishing a connection with minimal losses between the optical components and photodiodes co-integrated on a chip achieving a transmission efficiency of 70%. With this fully integrated PIC-based spectrometer interfaced to a spectral domain OCT system, we achieved a sensitivity of 92dB at an imaging speed of 55kHz, with a 6dB signal roll-off occurring at 2mm. We applied this innovative technology successfully to obtain 3D in vivo tomograms of zebrafish larvae and human skin. This ground-breaking fully integrated spectrometer represents a significant step towards a miniaturised, cost-effective, and maintenance-free OCT system.