Mironova Labs · technical resource
Application-Specific Process Notes
Integration guidance for high-k dielectrics, Cu interconnects, III-V passivation, and optical coatings
- Category
- Applications
- Zr / Cu / Gd Systems
High-k Gate & DRAM Capacitor Dielectrics (ZrO₂)
As DRAM scales sub-10 nm, capacitor dielectrics require ultra-low EOT combined with negligible leakage to maintain data retention. ALD ZrO₂ in MIM stacks (TiN/ZrO₂/TiN or Ru/ZrO₂/TiN) is the industry standard.
Notes & applicability
- Optimize Zr(TMHD)₄ with high-concentration O₃ at 390–400 °C to promote in-situ crystallization of the tetragonal ZrO₂ phase (k ≈ 30–40 vs ~20 for monoclinic).
- Total absence of residual halides prevents localized chemical corrosion of sensitive TiN bottom electrodes (a known failure mode with ZrCl₄).
- Target physical thickness: 5–8 nm. Below this, unacceptable leakage from direct quantum mechanical tunneling. Above this, capacitance density is insufficient for advanced nodes.
- Published dielectric performance for Zr(TMHD)₄-derived ZrO₂: k = 24–32, leakage 3.3 × 10⁻⁶ A/cm² at 1 MV/cm.
Cu Interconnects & Conformal Seed Layers
As interconnect pitch scales below 30 nm, PVD copper sputtering fails to provide continuous, conformal seed layers inside high-aspect-ratio vias. Discontinuous seeds cause fatal void formation during electrochemical plating.
Notes & applicability
- Integration stack: conformal ALD TaN diffusion barrier → ultra-thin ALD or PVD Ru liner → Cu(TMHD)₂ ALD seed (sub-5 nm).
- Cu(TMHD)₂ reduced by H-plasma nucleates seamlessly on Ru surfaces, yielding pinhole-free continuous seed layers capable of carrying plating current.
- Direct Cu ALD on bare TaN or SiO₂ without the Ru liner will result in agglomerated, highly resistive nanoparticles and typically results in via failure.
- Best reported Cu(TMHD)₂ film resistivity: ~1.78 µΩ·cm at 120 nm, approaching bulk Cu (1.68 µΩ·cm). At 20 nm: ~4.25 µΩ·cm due to grain boundary and surface scattering [R7].
III-V Channel Passivation (Gd₂O₃)
High-mobility InGaAs channels in advanced logic devices are plagued by interface trap states (Dᵢₜ) that pin the Fermi level, degrade carrier mobility, and destroy drive current. Gd₂O₃ from Gd(TMHD)₃ provides exceptional passivation.
Notes & applicability
- The Gd(TMHD)₃/O₃ process chemically assists in the thermodynamic displacement and reduction of problematic native arsenic and gallium oxides on the semiconductor surface.
- Optimized Gd₂O₃/InGaAs interfaces yield Dᵢₜ as low as ~10¹² eV⁻¹ cm⁻² with negligible frequency dispersion in C-V measurements.
- Published MOS data retains native SiO₂ at the interface — electrical values reflect Al/Gd₂O₃/native SiO₂/Si stacks, not pristine Gd₂O₃/Si interfaces. Interface-resolved characterization is needed for direct-on-Si targets.
- Leakage current for ~50 nm Gd₂O₃ at 300 °C: <2×10⁻⁸ A/cm² at 1 V (significantly better than Cp/H₂O-derived films at <5×10⁻⁷ A/cm²).
Optical Coatings & Photonics
Gd₂O₃ is used as a high-refractive-index, wide-bandgap material for laser optics, precision sensors, and photonic devices.
Notes & applicability
- The Gd(TMHD)₃/O₃ process is well-suited for optical applications: low residual carbon supports high transparency and reduced absorption across visible and near-IR spectra.
- The slow GPC (0.3 Å/cycle) is an asset here: it enables sub-nanometer precision in multilayer Distributed Bragg Reflectors (DBRs) and anti-reflective nanolaminates where absolute thickness control is prioritized over throughput.
- Surface roughness of ~1.2 nm rms at 250 °C (95 nm film) makes Gd(TMHD)₃-derived films suitable for optical interface quality requirements.
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.
Trends in Copper Precursor Development for CVD and ALD Applications
Gordon PG, Kurek A, Barry ST
Comprehensive review of Cu precursors. Cu(thd)₂ is fluorine-free (vs Cu(hfac)₂ HF corrosion), but industry trending toward Cu(I) amidinates for low-T metallic Cu ALD.
Atomic Layer Chemical Vapour Deposition of Copper
Mane AU, Shivashankar SA
Cu resistivities from ~4.25 µΩ·cm (20 nm) to ~1.78 µΩ·cm (120 nm) with excellent adhesion on TiN/TaN at 300 °C.
DOI 10.1016/j.mssp.2004.09.094Gadolinium 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.2005.08.002Plasma-Enhanced Atomic Layer Deposition and Etching of High-k Gadolinium Oxide
Vitale SA, et al.
PE-ALD using Gd(iPrCp)₃ + O₂ plasma: higher GPC (~1.4 Å/cycle at 250 °C) but narrower window and moisture sensitivity compared to Gd(thd)₃.
DOI 10.1116/1.3664756Gadolinium Scandate: Next Candidate for Alternative Gate Dielectric in CMOS Technology?
Fröhlich K, Fedor J, Kostič I, Maňka J, Ballo P
MOCVD GdScO₃ at 600 °C maintains amorphous phase through 1000 °C RTA, preventing grain boundary leakage. k > 20 for the ternary scandate (GdScO₃), not binary Gd₂O₃. Validates Gd-based ternary high-k dielectrics for advanced nodes.
DOI 10.2478/v10187-011-0009-z
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.