ams’ foundry services in optoelectronics broadens process options

August 13, 2015 // By Graham Prophet
An expanded process portfolio for ams’ (Graz, Austria) foundry users improves the potential sensitivity and form factor of advanced optoelectronic devices

The Foundry division of ams AG is extending its 0.35-µm CMOS optoelectronics IC foundry platform to offer chip designers greater sensitivity and precision and more light filtering capabilities. This platform is an add-on to the company’s ”More Than Silicon” portfolio, under which ams provides a package of technology modules, intellectual property, cell libraries, engineering consultancy and services to help customers successfully develop advanced analogue and mixed-signal circuit designs based on its speciality technologies.

ams’ dedicated optoelectronics foundry platform is based on an advanced 0.35 µm CMOS opto process. It includes technology enhancements and developments in the front end (at device level), in the back end (post-processing steps after wafer manufacturing) and at the package and assem-bly level.

At device level, ams now provides foundry customers with access to PN diodes that offer optimised responsivity at custom specific wavelengths (from blue to near infra-red) and minimised dark current rates, as well as a PIN diode combining very low capacitance with high quantum efficiencies.

In the back end of the wafer manufacturing process, the performance of optoelectronic devices can be further improved by applying various coatings on top of the CMOS wafer. ams has introduced anti-reflective coatings (ARCs) as well as interference filters: these are applied in the form of a stack of multiple, highly transparent oxides, allowing the realisation of highly accurate edge and bandpass filters (e.g. for IR and UV blocking), mirrors with precise reflectance, or beam splitters. Filter characteristics such as wavelength and slew rate can be specified over a wide range. In addition, applying adhesive colour layers (red, green, blue) optimised for certain wavelengths supports performance optimisation of light-sensitive devices.

Cost-effective, transparent plastic packages (substrate-based or lead frame-based) are available for low pin count ICs. Advanced 3D-WLCSP using ams’ own TSV (through-silicon via) technology enabling optimisation towards transmissivity, moisture level, temperature range and high pin counts, complete the package-level enhancements to ams’ opto platform.

Ams says that its