Conventional embedded Flash (eFlash) memories face serious limitations when trying to shrink below the 28 nm technology node, making further miniaturization difficult. To overcome this scaling challenge, Ferroelectric random access memories (FeRAM) offers compelling alternatives to eFlash as well as to DRAM and SRAM eventually, as it is intrinsically ultra-low power. Moreover the technology has evolved thanks to ultra-thin lead-free HfZrO₂ (HZO) ferroelectric films, which can be deposited below 10 nanometers in planar or vertical configurations while taking advantage of the high reliability and energy efficiency of HZO[1].

Recently, scientists from CEA-Leti took a step forward in overcoming scalability limitations by demonstrating for the first time a HZO-based ferroelectric capacitor (FeCap) BEOL platform at 22nm FDSOI technology node on 300 mm wafers and exploring the performances of 1T-1C FeRAM arrays thanks to an extensive statistical electrical characterization work.

This development, is fully pursued in the frame of FAMES pilot line as a key activity and output. The project brought a determinant contribution to accelerate the development of ferroelectric memory technology through collaborative work with key partners Fraunhofer and UCL and procurement of state-to-the-art equipment.

This achievement represents a major advance in ferroelectric memory technology, significantly advancing scalability for embedded applications and positioning ferroelectric RAM (FeRAM) as a competitive memory solution for advanced nodes.

Two types of integrations were demonstrated at scale on the 22 nm FD-SOI node :

• a conventional 2D planar ferroelectric capacitors (FeCAP) with a surface as small as 0.0028 µm²,
• a 3D vertical ferroelectric capacitor inserted in a via structure, enabling a capacitor surface 15 times larger than the 2D one for the same footprint.

The integration process has been optimized to obtain a relatively low thermal budget for HZO film crystallization compatible with the BEOL of the 22FDX and with no impact of the transistor performances.

These results were reported at the IEDM 2024 conference in San Francisco.

Thanks to its outstanding performances and competitive advantages such as non-volatility, high speed, high endurance and low energy consumption, FeRAM is extremely well positioned for being the next embedded memory solution for advanced FD-SOI nodes as the 10 and 7 nm.

This demonstration opens the door to faster, more energy-efficient, and cost-effective memory solutions in embedded systems such as IoT, mobile devices, and edge computing, and further strengthening Europe’s position in both the FD-SOI and the FeRAM Technologies.

[1] The high reliability of HZO through recent demonstration of product-level NV-DRAM for standalone applications has been reported by Micron (N. Ramaswamy et al., IEDM 2023)