Parallel imaging of the internal field in microscopic, hafnia-based ferroelectric capacitors for ultra-low power electronics

Full description

The exceptional scalability, compatibility with CMOS technology, non-volatility, low-power, and high-speed operation make hafnia-based ferroelectric devices promising contenders for next-generation memory applications [1]. Ferroelectricity in Hf0.5Zr0.5O2 (HZO) is attributed to the non-centrosymmetric polar orthorhombic (Pca21) phase. Oxygen vacancies (VO) stabilize the o-phase but too many VO favour the non-polar, tetragonal phase. The ongoing trend is to scale film thickness to 4-6 nm, in order to attain low operational voltage ~ 1V, compatible with advanced CMOS nodes and high-density 3D integration [2]. A compromise must be found between low operating voltage (for low power rating) and polarization switching (for maximum memory window), usually achieved at higher voltages.

However, at the ultrathin scale, the distribution of VO plays a crucial role in influencing device performance, potentially leading to reliability issues such as retention, endurance and imprint.

To quantify the correlations between VO distribution and device performance, spatially resolved X-ray Photoemission Electron Microscopy (XPEEM) will be employed on microscopic capacitor structures.

The spatial resolution of XPEEM will be used to locate and analyse each capacitor as a function of the applied bias used to set the polarization state by acquiring the Hf4f core level image series [3].

A dedicated X-ray source, implemented within the framework of the MicroElec focused project funded by the PEPR Diadem France 2030 programme, will allow imaging of multiple capacitor structures. Parallel imaging of microscopic, lithographically defined structures realized at CEA will allow direct probing of the device-to-device variability as a function of processing conditions and quantify the polarization magnitude as a function of the applied bias voltage.

Data analysis will simultaneously analyse multiple structures, using e.g. principal component analysis.

[1] Silva et al., Appl. Phys. Lett. Mater. 11, 089201 (2023)
[2] Cheema et al., Nature 604, 65-71 (2022)
[3] Hamouda et al., Appl. Phys. Lett. 120, 202902 (2022)

Location

CEA Saclay, (91) Essonne, France

Internship conditions

• Internship duration: 6 months
• Level of study: Bac+5
• Training: Master 2
• Continuation in PhD thesis: Yes
• Application deadline: 2 mars 2026

Useful methods and technics:
Photoelectron emission microscopy (NanoESCA), Photolithography, X-ray photoemission, Electrical characterization (Ferrotester TF1000)

Computer languages and software:
Igor Pro

Supervisor

Nick Barrett
Phone: 0622494273
Email :

Head of the laboratory

Nick Barrett
Phone: 0622494273