A CMOS-compatible morphotropic phase boundary

Abstract

Morphotropic phase boundaries (MPBs) show substantial piezoelectric and dielectric responses, which have practical applications. The predicted existence of MPB in HfO 2 -ZrO 2 solid solution thin film has provided a new way to increase the dielectric properties of a silicon-compatible device. Here, we present a new fabrication design by which the density of MPB r MPB and consequently the dielectric constant ò r of HfO 2 -ZrO 2 thin film was considerably increased. The r MPB was controlled by fabrication of a 10 nm [1 nm Hf 0.5 Zr 0.5 O 2 (ferroelectric)/1 nm ZrO 2 (antiferroelectric)] nanolaminate followed by an appropriate annealing process. The coexistence of orthorhombic and tetragonal structures, which are the origins of ferroelectric (FE) and antiferroelectric (AFE) behaviors, respectively, was structurally confirmed, and a double hysteresis loop that originates from AFE ordering, with some remnant polarization that originates from FE ordering, was observed in P-E curve. A remarkable increase in ò r compared to the conventional HfO 2 -ZrO 2 thin film was achieved by controlling the FE-AFE ratio. The fabrication process was performed at low temperature (250 °C) and the device is compatible with silicon technology, so the new design yields a device that has possible applications in near-future electronics.

Hafnium Oxide (HfO2) – A Multifunctional Oxide: A Review on the Prospect and Challenges of Hafnium Oxide in Resistive Switching and Ferroelectric Memories

“…[279] Indeed, a relatively large electronic bandgap E G combined with a high ε r gives elbow room to creative researchers toward the fabrication of ideal high-κ devices (Figure 3). [280][281][282][283] HfO 2 -based ultrathin films solved the scaling issues, and since 2007, INTEL group has practically used this material as a new high-κ for commercial production of the latest microprocessors. [279] To enhance the scaling ability of the emerging devices, improving the dielectric properties of HfO 2 -based thin film has always been on demand.…”

“…region in the graph of E G versus ε r (Figure 3), [281,282] numerous theoretical and experimental studies have been performed. For this purpose, different paths have been explored to obtain a reliable and highly efficient dielectric material in the semiconductor industry.…”

“…A novel approach based on the existence of morphotropic phase boundaries (MPB) was recently developed. [281,283,[292][293][294][295] This approach introduced a substantial improvement in the dielectric properties of HfO 2 -based thin films. In fact, the discovery of ferroelectricity and anti-ferroelectricity in HfO 2 -ZrO 2 (HZO) solid solution thin films [246][247][248][249][250][251][252][253][254][255][256][257][258][259][260][261][262] paved the way for enhancing dielectric properties through MPB, which will be discussed later in Section 8.…”

“…Therefore, it provides an alternative approach to boost the dielectric constant ε r without degrading the bandgap. [281] MPB ceramics, such as PZT, are the basis of a wide range of piezoelectric and dielectric technologies, such as high-κ materials, smart systems, sensors, actuators, ultrasound generation, and underwater acoustics. The existence of MPB inside HfO 2 -ZrO 2 solid solutions was for the first time suggested by Park et al, [295] who investigated the ferroelectric behaviors of different solid solution Hf 1-x Zr x O 2 films as a function of film thickness.…”

“…Recently, Kashir et al [281,283] investigated the coexistence of o-HZO and t-ZrO 2 phases by fabrication of a 10-nm FE Zr-doped HfO 2 AFE ZrO 2 nano-laminated thin film. The coexistence of t-and o-phases were clearly shown by structural analysis.…”