HZO05 ZRO2 and HZO05Z thin films deposited on silicon substrates exhibit distinct structural changes after rapid thermal annealing, as revealed by X-ray diffraction (XRD) patterns. This study focuses on how RTA conditions influence crystallinity, preferred orientation, and defect states in these ceramic films.
By correlating XRD peak positions, intensities, and full width at half maximum (FWHM), researchers can quantify phase stability, grain growth, and residual stress induced by RTA. The following sections detail the experimental workflow, phase identification, and film performance implications for HZO-based materials.
| Sample | Film Composition | RTA Temperature | Dominant Phase |
|---|---|---|---|
| HZO05 ZRO2 | Hf0.5 Zr0.5 O2 | 300°C | Monoclinic + Amorphous |
| HZO05 ZRO2 | Hf0.5 Zr0.5 O2 | 400°C | Tetragonal + Monoclinic |
| HZO05Z | Hf0.5 Zr0.5 O2 | 400°C | Tetragonal dominant |
| HZO05Z | Hf0.5 Zr0.5 O2 | 500°C | Highly textured Tetragonal |
XRD Phase Identification and Crystallinity after RTA
XRD phase identification for HZO05 ZRO2 and HZO05Z thin films after RTA shows a shift from mixed monoclinic–tetragonal toward a dominant tetragonal structure as temperature increases. Higher RTA temperatures promote grain growth and reduce amorphous content, sharpening diffraction peaks and improving film texture.
Peak position shifts indicate changes in lattice parameters, reflecting stress relaxation and cation ordering within the HfO2–ZrO2 system. For HZO05Z films, intense (111) and (200) tetragonal peaks demonstrate enhanced preferential orientation, which is critical for ferroelectric and dielectric applications requiring high performance and low leakage currents.
Key XRD Metrics by Sample and Temperature
FWHM values decrease with rising RTA temperature, indicating improved crystallinity. The tetragonal-to-monoclinic phase ratio increases in HZO05Z, especially at 500°C, where the films exhibit minimal monoclinic contamination. In HZO05 ZRO2, residual compressive strain is observed at 300°C but relaxes near 400°C, leading to more stable lattice dimensions.
Microstructural Evolution and Grain Growth
Microstructural evolution derived from XRD patterns demonstrates that grain size grows with RTA temperature, as inferred from Scherrer calculations. HZO05Z thin films show significantly larger grains compared to HZO05 ZRO2 under the same thermal budget, resulting in fewer grain boundaries and improved electrical properties. This evolution directly impacts device reliability, leakage current, and switching behavior in memory and sensor applications.
Preferred orientation strengthens with higher temperature annealing, reducing random leakage paths and enhancing endurance. The texture coefficient calculated from XRD intensities confirms that HZO05Z films processed at 500°C possess superior (200) pole alignment, which is advantageous for scaled ferroelectric field-effect transistors (FeFETs) requiring consistent threshold voltage and switching uniformity.
Stress, Strain, and Lattice Parameters from XRD
XRD patterns enable the extraction of stress and lattice parameters, revealing how RTA modifies internal strain in HZO05 ZRO2 and HZO05Z thin films. Compressive stress observed at lower temperatures transitions toward near-zero or slight tensile stress at optimal annealing conditions, balancing mechanical stability and electrical performance. These changes correlate with shifts in (222) and (200) peak positions, indicating altered Hf–O–Zr bonding configurations and cation distribution.
For HZO05Z, lattice expansion along the c-axis is consistent with improved tetragonal stability, supporting high remnant polarization in downstream ferroelectric measurements. Accurate modeling of strain and lattice distortion is essential for predicting film behavior under cyclic electrical loading and temperature variations.
Recommendations for Optimizing HZO05 ZRO2 and HZO05Z Thin Films
- Select RTA temperatures near 400–500°C to maximize tetragonal phase and texture in HZO05Z films.
- Monitor FWHM and peak positions to assess crystallinity, stress, and phase stability after annealing.
- Balance thermal budget to avoid excessive grain growth that may degrade interface control in scaled devices.
- Leverage preferred orientation for high-performance FeFETs by tailoring deposition and RTA conditions.
FAQ
Reader questions
How does RTA temperature affect the phase distribution in HZO05 ZRO2 films?
Increasing RTA temperature shifts HZO05 ZRO2 from mixed monoclinic–tetrahedral toward a higher tetragonal fraction, reducing amorphous content and monoclinic peaks around 400°C.
What role does texture play in HZO05Z films after RTA?
Higher RTA temperatures enhance (200) preferred orientation in HZO05Z films, resulting in improved grain alignment, lower leakage current, and more reliable switching behavior for FeFET devices.
Why are XRD peak positions important for stress analysis in these films?
Shifts in peak positions reflect changes in lattice parameters and internal strain, indicating stress relaxation or compression that influences film adhesion, mechanical stability, and electrical performance.
What is the relationship between grain size and electrical properties post RTA?
As RTA temperature increases, grain size grows and grain boundary density decreases, leading to reduced leakage current, higher breakdown strength, and improved endurance in HZO-based thin films.