Mironova Labs · technical resource
Film Characterization Checklist
Metrology workflow for verifying ALD regime and film quality
- Category
- Analytical
- All TMHD Films
Thickness, Uniformity & Density
Primary tools for rapid, non-destructive thickness mapping and density determination of TMHD-derived thin films.
Notes & applicability
- Spectroscopic Ellipsometry (SE): Use a Cauchy optical dispersion model for transparent dielectrics (ZrO₂, Gd₂O₃). Expected refractive index n at 633 nm for high-quality ALD ZrO₂: 2.10–2.20. A significantly lower n (<2.0) indicates substantial carbon contamination, porosity, or low film density.
- For metallic Cu from Cu(TMHD)₂: SE modeling requires a multi-oscillator Drude-Lorentz model. A 4-point probe sheet resistance measurement is more practical.
- X-Ray Reflectivity (XRR): Essential for ultra-thin films (<10 nm) to determine absolute physical thickness, interfacial layer thickness, and electron density independent of optical models. Target density for ALD ZrO₂ at 375–400 °C: 5.6–5.8 g/cm³.
- Gd₂O₃ from Gd(TMHD)₃/O₃: Thickness uniformity at window temperatures (250–300 °C) is ~1–2% over 10 cm flow direction. Surface roughness ~1.2 nm rms (95 nm film at 250 °C).
Composition & Impurities (XPS Analysis)
XPS is the gold standard for detecting the most critical issue with TMHD precursors: carbon contamination from incomplete ligand combustion. Monitor specific core-level binding energies to confirm correct oxidation states and detect residual carbon.
| Element / Level | Target Compound | Binding Energy (eV) | Interpretation |
|---|---|---|---|
| Zr 3d₅/₂ | ZrO₂ | 182.3–183.6 | Fully oxidized Zr⁴⁺ state |
| Cu 2p₃/₂ | Cu metal | 932.4 | Cu⁰ metallic state |
| Cu 2p satellites | CuO (unwanted) | 940–945 | Incomplete reduction → residual Cu²⁺ |
| Gd 4d | Gd₂O₃ | 142.0–147.4 | Oxidized Gd³⁺ state |
| C 1s (carbonate) | Residual carbon | ~289 | Uncombusted carboxylate/carbonate groups |
Notes & applicability
- Optimized Zr(TMHD)₄/O₃ at 375 °C: carbon drops below XPS detection limit (~0.2 at.% by TOF-ERDA). Below 300 °C, residual carbon can exceed 5–10 at.%, degrading dielectric breakdown strength.
- Gd(TMHD)₃/O₃ carbon trend: 9–15 at.% at 225 °C → 7 at.% at 250 °C → 2.3 at.% at 300 °C. Temperature is the primary lever for carbon reduction.
- FTIR can supplement XPS to detect carbonate impurities in Gd₂O₃ films.
Crystallinity & Phase
The crystallographic phase directly dictates dielectric constant and electrical performance.
Notes & applicability
- Grazing Incidence XRD (GIXRD): For ZrO₂, as-deposited films are typically a polycrystalline mix of monoclinic and orthorhombic/tetragonal phases. Post-deposition annealing drives transformation to the high-k tetragonal phase (k ≈ 30–40 vs ~20 for monoclinic).
- For Gd₂O₃: Films below 250 °C are amorphous. Above 250 °C, crystalline cubic C-type (bixbyite) structure with dominant (400) reflection. Effective k ≈ 9–13 depending on process conditions.
- Cu from Cu(TMHD)₂: Resistivity is the practical quality metric rather than phase analysis. Best reported: ~8 µΩ·cm at 60 nm thickness on Ru/Pt seed.
Interface Quality
For advanced device integration, interface quality is as important as bulk film properties.
Notes & applicability
- Cross-sectional HRTEM: Evaluate and quantify parasitic interfacial oxide layers on Si substrates. For Gd₂O₃ on GaAs/InGaAs, validate complete absence of parasitic As₂O₃ at the semiconductor boundary to confirm clean ALD nucleation.
- For MOS structures: native SiO₂ presence affects measured overall permittivity. Published Gd₂O₃ MOS data includes native oxide interface — account for this when comparing to direct-on-Si targets.
- Leakage current density benchmarks: Gd(TMHD)₃/O₃ at 300 °C, ~50 nm film: <2×10⁻⁸ A/cm² at 1 V.
References
Zirconia Thin Films by Atomic Layer Epitaxy: A Comparative Study on the Use of Novel Precursors with Ozone
Putkonen M, Niinistö J, Kukli K, et al.
Zr(thd)₄/O₃ ALD window at 375–400 °C, GPC 0.24 Å/cycle, monoclinic ZrO₂ with <0.5 at.% C and H impurities by TOF-ERDA.
DOI 10.1039/B105272CAtomic Layer Deposition of ZrO₂ Thin Films Using Zr(thd)₄ and Ozone
Niinistö J, et al.
Confirms self-limiting growth plateau at 375–400 °C with 0.24 Å/cycle GPC. ZrO₂ films exhibit k = 24–32 and leakage of 3.3 × 10⁻⁶ A/cm² at 1 MV/cm.
Gadolinium Oxide Thin Films by Atomic Layer Deposition
Niinistö J, Petrova N, et al.
Gd(thd)₃/O₃ ALD: self-limiting at ~300 °C, GPC ~0.3 Å/cycle. Film impurities: ~2.3 at.% C, ~1.7 at.% H. Cubic C-type Gd₂O₃ above 250 °C.
DOI 10.1016/j.jcrysgro.2005.08.002Chlorine Contamination in HfO₂ Films Deposited by ALD Using HfCl₄
Park PK, Kang S-W, et al.
HfCl₄/H₂O ALD leaves 1–3 at.% residual Cl at ~300 °C, acting as electron traps that degrade dielectric performance. Halide-free precursors eliminate this.
DOI 10.1021/acs.jpcc.5b05286
Evaluate our precursors
Mironova Labs manufactures electronic-grade TMHD precursors in Fairfield, NJ. Request evaluation quantities for qualification against your process recipes.
Safety & regulatory notice
- For research use only. Process parameters must be verified and optimized for your specific reactor, substrate, and integration requirements.
- Consult the Safety Data Sheet (SDS) for each precursor and co-reactant before use. Some processes involve hazardous materials (ozone, hydrogen plasma, HF-containing etchants, hydrazine-class reductants) that require specialized training, engineering controls, and institutional safety review.
- Performance benchmarks cited are drawn from published literature under specific conditions. Actual results depend on equipment, process integration, and substrate preparation.
- Mironova Labs supplies precursor materials only. Film properties and device performance are the responsibility of the process integrator.