Samco Details SiO₂ Quasi-ALE Etch-Rate Stabilization Using O₂ Plasma at ALD/ALE 2026

By NineScrolls Team · 2026-07-30 · 4 min read · Industry

1. What Was Presented

Samco Inc. presented a poster titled "Stabilization of Etch Rate in SiO₂ Quasi-ALE Using an O₂ Plasma" at ALD/ALE 2026 — the AVS 26th International Conference on Atomic Layer Deposition, featuring the 13th International Atomic Layer Etching Workshop — held June 28 to July 1, 2026 at the JW Marriott Water Street in Tampa, Florida. The work appeared as poster ALE-MoP-3 during the Atomic Layer Etching poster session on June 29.

The research targets a concrete process problem: keeping the per-cycle etch amount in silicon dioxide quasi-atomic-layer etching stable and repeatable from run to run. That stability is the difference between a laboratory demonstration and a manufacturable etch step.

2. What "Quasi-ALE" Means and Why SiO₂ Is Difficult

True atomic layer etching removes material one atomic layer at a time by separating the process into two self-limiting half-cycles: a surface-modification step (for example, chemical adsorption that forms a reactive layer) followed by a low-energy ion or plasma step that removes only the modified layer. When the two steps are self-limiting, the etch amount per cycle is fixed and independent of small fluctuations in time or flux — the property that makes ALE so attractive for low-damage, atomically controlled removal.

SiO₂ is one of the harder materials to hold in a clean self-limiting window. The fluorocarbon chemistries typically used to etch oxide can accumulate or deplete polymer on the surface across cycles, so the effective etch rate drifts rather than staying flat. Processes in this regime are often called "quasi-ALE": they behave like ALE but are not perfectly self-limiting, which is exactly why etch-rate drift is the headline challenge Samco's poster addresses.

3. The O₂ Plasma Stabilization Approach

Samco's contribution is the use of an O₂ plasma step to stabilize the SiO₂ quasi-ALE etch rate. An oxygen plasma removes excess carbon-bearing residue from the surface between reactive steps, resetting the starting condition of each cycle so that polymer neither builds up nor runs out over a long sequence.

The practical payoff is a more constant etch-per-cycle across many cycles and better run-to-run repeatability — the two metrics that determine whether a quasi-ALE recipe can be trusted to hit a target depth reliably. Samco framed the result as a contribution to ongoing technical discussion around plasma-based etching and ALE process control for next-generation device manufacturing.

4. Why Etch-Rate Stability Decides Advanced-Node Yield

As device structures shrink and stack vertically, the tolerance on how much material an etch step removes keeps tightening. Gate-all-around transistors, high-layer-count 3D NAND, and DRAM capacitor structures all depend on removing dielectric to within a few angstroms of a target, uniformly across the wafer and identically from wafer to wafer.

An etch rate that drifts even slightly per cycle compounds over a multi-cycle recipe into a meaningful depth error, showing up downstream as parametric variation or yield loss. This is why atomic-scale etch control — and the process-stability tricks that make it repeatable — has moved from a research curiosity to a production requirement. The distinctions between conventional plasma etch regimes and higher-density, better-controlled approaches are covered in our explainer on the differences between PE-RIE and ICP-RIE plasma etching.

5. NineScrolls Niche Angle

For plasma-processing labs, the significance is that competitive dielectric etching is increasingly won on control, not raw speed. A stable etch-per-cycle, clean surface conditioning between steps, and run-to-run repeatability are becoming the purchase-decision metrics for advanced etch tools — the same shift we saw in recent research-scale ICP-DRIE selections.

Teams building toward atomic-scale oxide etching should understand the underlying plasma-source physics first. Our reactive ion etching guide covers the fundamentals of reactive-ion dielectric etching, and our overview of ICP-RIE technology for advanced etching explains why inductively coupled sources give the independent control of ion energy and ion density that low-damage, self-limiting etch regimes require. On the supply-chain side, quasi-ALE and ALE processes lean heavily on precise, fast-switching gas delivery (alternating reactive and O₂ conditioning chemistries), stable low-energy plasma generation, and clean chamber-wall conditions — the plasma-source, gas-delivery, and vacuum subsystems that separate a repeatable atomic-scale etcher from an unstable one.