Ferroelectric hafnium oxide varactors for tunable active millimeter wave devices

In this project, Fraunhofer IPMS is developing and validating devices based on ferroelectric thin-film hafnium oxide varactors. The primary active component for demonstration purposes will be a voltage-controlled oscillator (VCO).

The main areas of focus are:

• Chip design and implementation: Development of active high-frequency components such as oscillators and phase shifters in CMOS technology, with a view to compact, high-performance implementation
• BEoL integration and validation: Integration of hafnium oxide varactors into the back-end-of-line (BEoL) layers of CMOS manufacturing, coordination with industrial customers for subsequent production
• Characterization: Research into how well these components perform at high frequencies, how well they can be controlled, and how reliably they withstand temperature changes
• System integration: Integration of the components into circuits and close coordination with partners for real-world application testing

Our goal is to advance to integrated chip systems with a maturity level of TRL 5.

The use of ferroelectric hafnium oxide enables greater energy efficiency to be achieved. The components are miniaturized and less susceptible to temperature fluctuations. Increased linearity in tuning also leads to significant advances in component architecture. Since they can also be manufactured using CMOS technology, which is the industrial standard in microelectronics manufacturing, the result is ideal scalability and cost efficiency.