Our deposition methods, in plain English.
Heard of ALD but aren’t a specialist? Start here, then explore the systems and the published research that put these methods to work.
ALD, PE-ALD, and MLD at a glance.
| Method | What it is | Best for |
|---|---|---|
| Atomic Layer Deposition (ALD) | Two precursor gases are pulsed in turn; each reacts only with the surface left by the last, one self-limiting cycle at a time. Builds inorganic films such as oxides, nitrides, metals. | Atomic-scale thickness control and conformal coating of deep trenches, pores, and 3D shapes for semiconductors, batteries, catalysts, and optics. |
| Plasma-enhanced ALD (PE-ALD) | ALD with a plasma to activate the reaction, for lower process temperatures and denser films. Works for nitrides and metals that thermal ALD struggles with. | Broader chemistry at lower temperature. Supported on the GEMStar XT-P and PRIME variants. |
| Molecular Layer Deposition (MLD) | ALD’s organic cousin. MLD builds organic and hybrid organic–inorganic layers from bifunctional organic molecules, one self-limiting step at a time. | Flexible, functional coatings for battery-electrode protection and tunable membranes. MLD and ALD run together can produce new functionalized nanomaterials. |
How ALD actually works.
How ALD & MLD relate to other thin-film deposition methods
ALD is CVD, split in two
ALD is a specialized form of chemical vapor deposition (CVD). In ordinary CVD, two precursors enter the chamber at once and react in the gas phase, growing film wherever they meet. ALD splits that single reaction into two half-reactions and separates the precursors in time: each is pulsed in, reacts only with the surface, then is purged away before the next arrives. That makes ALD a surface-mediated, self-limiting process rather than a gas-phase one.
Diffusion-controlled (CVD)
Reaction-controlled (ALD)
One growth cycle, step by step
A single cycle adds a fraction of an atomic layer; the steps repeat until the target thickness is reached. Thermal Al₂O₃ growth is the classic example:
- Precursor pulse (A) — trimethylaluminum, Al(CH₃)₃, is pulsed in and bonds to the surface until every available site is filled, then stops. This self-limiting step is what gives ALD its atomic-scale control.
- Purge — inert gas and the pump clear excess precursor and the CH₄ by-product.
- Reactant pulse (B) — water vapor, H₂O, reacts with that layer to form Al₂O₃ and regenerate a fresh, reactive surface.
- Purge — excess water and by-products are pumped away, leaving the surface ready for the next cycle.
Why it matters: conformality
Because growth is limited by surface reactions rather than by how reactant diffuses in — as it is in CVD — every exposed surface is coated equally, even deep inside pores and high-aspect-ratio (large length-to-diameter) trenches. The payoff is conformal, pin-hole-free films of precisely controlled thickness on complex 3D geometry, such as alternating Ta₂O₅ and Al₂O₃ layers lining deep trenches in silicon.
Recipes and films we routinely run.
A reference of common materials and the systems they run on. The full, searchable evidence base lives in the Research Library.
| Material | Type | Representative use |
|---|---|---|
| Al₂O₃ | Thermal / PE-ALD | Encapsulation, tunnel barriers, area-selective ALD |
| TiO₂ | Thermal / PE-ALD | Photocatalysis, optical layers, DNA sensing |
| SnO₂ | Thermal ALD | Perovskite solar-cell electron transport layers |
| ZnO | Thermal ALD | Antibacterial coatings, transparent conductors |
| Pt | Thermal / PE-ALD | Catalysis, electrodes |
| Lithicone (MLD) | MLD | Li-ion electrode protection |
Ready to talk specifics?
Tell us the film you need and the substrate it’s going on. We’ll point you to a system, a service, or the relevant published work.
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