Low-thermal-budget (300 °C) ferroelectric TiN/Hf0.5Zr0.5O2/TiN capacitors realized using high-pressure annealing

Abstract

In this Letter, a high-pressure annealing (HPA) process is proposed as a way to reduce the thermal budget of Hf0.5Zr0.5O2 (HZO) thin films with ferroelectric behaviors. The low-thermal-budget process is essential for integrating ferroelectric devices in the back-end-of-line to provide more functionalities and effective memory area. For the HZO film annealed at 300 °C using the HPA process, an orthorhombic phase responsible for ferroelectric behavior was formed with a decrease in film thickness, resulting in a remanent polarization (Pr) of ∼13 μC/cm2 (i.e., 2Pr of ∼26 μC/cm2). Meanwhile, when only the annealing time was increased at 300 °C without applying pressure, the HZO film did not crystallize and exhibited linear dielectric properties. Consequently, the HZO films (<10 nm) can be crystallized by applying pressure (15 atm) even at low temperatures of 300 °C, thereby obtaining ferroelectric properties.

Sputtered Ferroelectric Hafnium–Zirconium Oxide with High Remanent Polarization after Back-End-of-Line Compatible Annealing

“…After BEOL-compatible annealing of 400 °C for 1 h and electric wake-up, the sputtered HZO FeCap could exhibit a 2 P r of 36 μC/cm 2 and an endurance of up to 10 7 cycles. In this work, the FE properties of the sputtered HZO samples approach the FE properties of ALD-deposited HZO samples of a similar thickness with a 400 °C annealing, which was reported to have the 2 P r and endurance of about 40 μC/cm 2 and 10 7 to 10 8 cycles, respectively . Since sputtering is a non-equilibrium process and sputtered HZO has not been studied as much as ALD-deposited HZO, one could expect that sputtered HZO FeCaps have the potential to reach the same FE properties as ALD-deposited HZO FeCaps.…”

“…In this work, the FE properties of the sputtered HZO samples approach the FE properties of ALD-deposited HZO samples of a similar thickness with a 400 °C annealing, which was reported to have the 2P r and endurance of about 40 μC/cm 2 and 10 7 to 10 8 cycles, respectively. 36 Since sputtering is a non-equilibrium process and sputtered HZO has not been studied as much as ALD-deposited HZO, one could expect that sputtered HZO FeCaps have the potential to reach the same FE properties as ALD-deposited HZO FeCaps. In addition, the higher throughput makes sputtering an excellent alternative technique to ALD to fabricate HZO-based FeCaps in BEOL processes.…”

Low Operating Voltage, Improved Breakdown Tolerance, and High Endurance in Hf0.5Zr0.5O2 Ferroelectric Capacitors Achieved by Thickness Scaling Down to 4 nm for Embedded Ferroelectric Memory

“…It should be noted that the crystallization temperature depends not only on the film thickness but also on the film deposition technique, interface between the ferroelectric and electrode, , annealing time, and annealing pressure . That is, the temperature-thickness mapping in Figure applies to HZO films that are deposited by ALD at 300 °C with water as an oxidant, capped with TiN, and annealed under a nitrogen atmosphere for 30 s, but the opportunity to lower the crystallization temperature limit by material and process engineering does remain.…”

Relaxation Induced by Imprint Phenomena in Low-Temperature (400 °C) Processed Hf0.5Zr0.5O2-Based Metal-Ferroelectric-Metal Capacitors

“…Among various doped HfO 2 films, Zr-doped HfO 2 , that is, Hf 0.5 Zr 0.5 O 2 (HZO), is one of the most promising candidates because of its low crystallization temperature (≤400 °C), stable FE properties for a wide range of compositions, and back-end-of-line (BEOL) compatibility. 1,3,7,16 Although HZO films have shown promising performances, such as suitable remanent polarization (P r ≈ 25 μC/cm 2 ), low voltage operation (2.0 V), and nanosecond switching, 17 careful assessments of the reliability properties are needed to ensure the practical realization of these FE films.…”

“…This is because HfO 2 is a material that is fully compatible with current complementary metal-oxide-semiconductor (CMOS) technology, making ferroelectricity one of the most promising emerging memories. − Additionally, the FE properties in thin doped HfO 2 films can be easily obtained using atomic layer deposition (ALD), a technique that enables precise control of film thickness and three-dimensional (3-D) conformality. − In this regard, there has been a growing interest in investigating these materials for a wide range of device applications like ferroelectric random-access memory (FRAM), ,, ferroelectric field-effect transistors (FeFETs), , energy storage, , and even neuromorphic , applications. Among various doped HfO 2 films, Zr-doped HfO 2 , that is, Hf 0.5 Zr 0.5 O 2 (HZO), is one of the most promising candidates because of its low crystallization temperature (≤400 °C), stable FE properties for a wide range of compositions, and back-end-of-line (BEOL) compatibility. ,,, Although HZO films have shown promising performances, such as suitable remanent polarization ( P r ≈ 25 μC/cm 2 ), low voltage operation (2.0 V), and nanosecond switching, careful assessments of the reliability properties are needed to ensure the practical realization of these FE films.…”