Experimental RF Characterization of Ferroelectric Hafnium Zirconium Oxide Material at GHz for Microwave Applications

摘要

The discovery of doped Hafnium based ferroelectric materials has attracted enormous attentions due to their full compatibility with silicon CMOS technology and excellent scalability towards advanced technology nodes (e.g., 22 nm or beyond) [1]. The doped HfO2-based ferroelectric materials have been researched extensively for nonvolatile memory devices [1], [2]. There are proposals using them for tunable microwave devices such as bandpass filters and phase shifters [3] - [5]. However, these prior research efforts on microwave device designs rely on the kHz low frequency C-V characteristics and study high-frequency GHz tunable microwave devices based on electromagnetic simulations and the unverified assumption of frequency-independent material property [8-9]. This work experimentally characterizes the RF characteristics of Hafnium Zirconium Oxide (HZO) [1]. We fabricated a set of microwave test structures using the metal-oxide-metal (MOM) plate capacitor. MOM capacitors ensure uniform electrical field through the HZO material-under-test and thus will report more accurate material property characterization than interdigitated capacitors. Our recent work [6] uses similar HZO stack but presents the small signal AC response only from 1kHz to 10MHz, though it reveals interesting device physics such as domain pinning effect. In this paper, our measurements use large-signal quasi-DC sweep for the HZO material biasing, as well as the small signal S-parameter measurements for AC capacitance extraction from 10MHz to 2GHz range, highest reported frequency thus far.