Fig. 4. Influence of reactant exposure time and temperature on the sample mass changes during thermal ALE  $\mathrm{Al}_2\mathrm{O}_3$  films using TMA and HF. (I): effect of TMA (a) and HF (b) exposure time on mass changes ( $\Delta \mathrm{M}_{\mathrm{TMA}}$  and  $\Delta \mathrm{M}_{\mathrm{HF}}$ ) at  $300^{\circ}\mathrm{C}$ , respectively; (II): effect of temperature on  $\Delta \mathrm{M}_{\mathrm{TMA}}$  and  $\Delta \mathrm{M}_{\mathrm{HF}}$  of TMA, HF half-reaction (a) and mass change per ALE cycle (MCPC). Reproduced from Ref. [28].

A line chart showing the change in ΔMTMA with increasing TMA exposure time at 300°C.

A multiple line chart showing the change ΔMTMA, and ΔMHF as a function of the exposure time.

A line chart showing the change in ΔMHF with increasing HF exposure time at 300°C.

A line chart showing the change in MCPC as a function of the temperature, between 250 and 325  °C.

| TMA Exposure Time (s) | ΔMTMA (ng/cm2 cycle)) |
| --- | --- |
| 0.0 | 0 |
| 1.0 | -20 |
| 2.0 | -30 |
| 3.0 | - |

| Exposure time | ΔM HF | ΔM TMA |
| --- | --- | --- |
| - | 5 | -10 |
| - | 10 | -20 |
| - | 18 | -30 |
|  | 20 | -40 |

| HF Exposure Time (s) | ΔMHF (ng/cm2 cycle)) |
| --- | --- |
| 0.0 | 0 |
| 0.5 | 12 |
| 1.0 | 14 |
| 1.5 | 15 |
| 2.0 | - |

| Temperature (°C) | MCPC (ng/cm2 cycle)) |
| --- | --- |
| 250 | 0 |
| 275 | -10 |
| 300 | -18 |
| 325 | -20 |

Answer: The lower temperature, i.e. 250 °C

Answer: As the temperature increases, the amount of mass that changes per cycle decreases, slowing the ALE cycle down.

Answer: As can be seen in the subfigure, the mass change increases with the exposure time for HF, but decreases for TMA.

Answer: The mass changes of the samples, in this case for HF, are shown as a function of the HF exposure time (s).

icdar2026-competition-data/train/atomic-layer-etching/simulation-usecase/24/Review Paper -- Thermal atomic layer etching Mechanism, materials and prospects.pdf


The chart illustrates how the etching yield of silicon nitride (Si₃N₄) during HF exposure varies with the angle of incidence (θₐₙ) of incoming particles. The yield remains nearly constant around 0.06 between 0° and 30°, then slightly increases to a peak of 0.07 at 45°. Beyond this angle, the etching yield decreases markedly, reaching approximately 0.03 at 75°. This trend indicates that normal to moderately angled incidence promotes optimal etching, while highly oblique angles reduce etching efficiency, likely due to reduced energy transfer or surface access.

| θin (deg) | Etching yield (Si3N4/HF) |
|---|---|
| 0 | 0.06 |
| 15 | 0.06 |
| 30 | 0.06 |
| 45 | 0.07 |
| 60 | 0.05 |
| 75 | 0.03 |

Answer: The etching yield remains relatively stable between 0° and 30°, with values around 0.06. At 45°, the yield slightly increases to 0.07, suggesting enhanced surface interaction at this moderate angle. However, beyond 45°, the etching yield decreases significantly, dropping to 0.03 at 75°. This implies that more oblique angles reduce the effectiveness of etching, likely due to lower surface impact or inefficient energy transfer from incident particles.

Answer: Yes

Answer: 45 degrees.

Answer: Maximum etching efficiency occurs near 45°, Minimal change is seen from 0° to 30° , Avoid high angles (≥ 60°), reactor design should consider angular effects.

icdar2026-competition-data/train/atomic-layer-etching/simulation-usecase/33/Atomistic Simulation of HF Etching Process of Amorphous.pdf


Figure 9. (a) The reflection coefficient, and (b) the total etching yield per incident HF molecule, both as a function of the incident angle. The error bars indicate the standard deviations among three independent runs.

The figure presents the variation of reflection coefficient as a function of incident angle (θin) from 0° to 75°. From 0° to 45°, the reflection coefficient remains relatively constant at around 0.1, indicating minimal reflection changes over low to moderate angles. At 60°, the coefficient begins to rise, and at 75°, it increases sharply to approximately 0.45. This indicates that higher incident angles lead to significantly more surface reflection, a behavior that may influence energy input or beam penetration in angle-sensitive surface processes.

| θin (deg) | Reflection coefficient |
|---|---|
| 0 | 0.1 |
| 15 | 0.1 |
| 30 | 0.1 |
| 45 | 0.1 |
| 60 | 0.2 |
| 75 | 0.45 |

Answer: The reflection coefficient remains relatively stable at around 0.1 between 0° and 45°, suggesting minimal angle dependence in that range. However, beyond 60°, the coefficient increases substantially, reaching approximately 0.45 at 75°. This trend indicates that reflection becomes significantly more pronounced at high angles of incidence, which could affect energy deposition or reaction efficiency in angle-sensitive processes.

Answer: At 60 degrees

Answer: No

Answer: Minimise angles above 60° , Maintain angles between 0° and 45° , Adjust beam alignment in plasma


Figure 5. (a-d) Snapshots representing the  $\mathrm{H}_2\mathrm{O}$  formation mechanism obtained in optimization of the  $\mathrm{O}_5$  configuration, as shown in Figure 3 (the color code is the same). The left panel shows a complementary graph with relative energy along the formation pathway with respect to the initial geometry (desorbed oxygen atoms).

icdar2026-competition-data/train/atomic-layer-etching/simulation-usecase/35/Density Functional Theory Study of Oxygen Adsorption on Polymer Surfaces for Atomic-Layer.pdf


Figure 1. Etch per cycle for TiN films versus  $\mathrm{NbF}_5$  pulse time at  $460^{\circ}C$  The duration of  $\mathbb{N}_2$  purges and  $\mathrm{CCl}_4$  pulses were fixed at 6 and 1 s, respectively.

The figure illustrates how the etch per cycle of TiN films varies with NbF₅ pulse time during the NbF₅–CCl₄ etch process at 460 °C. The etch per cycle increases from about 0.3 Å without NbF₅ to approximately 0.8 Å at a 3 s NbF₅ pulse, showing a gradual increase without clear saturation under the applied conditions.

| NbF₅ pulse time [s] | Etch per cycle [Å] |
|---|---|
| 0.0 | 0.3 |
| 1.0 | 0.6 |
| 3.0 | 0.8 |

Answer: Yes

Answer: The etch per cycle increases with increasing NbF₅ pulse time. When no NbF₅ is used, the etch per cycle is about 0.3 Å, indicating that CCl₄ alone can etch TiN. As the NbF₅ pulse time increases to 1 s, the etch per cycle rises to approximately 0.6 Å, and further increases to about 0.8 Å at a 3 s pulse time. The trend shows a gradual increase without clear saturation.

Answer: Partially self-limiting surface reactions, Insufficient purge time, Low volatility or slow removal of reaction products, Presence of residual CCl₄ vapors in the etch system, Slow diffusion of fluorine species through TiN grain boundaries

Answer: Approximately 0.6 Å.

icdar2026-competition-data/train/atomic-layer-etching/simulation-usecase/4/Combining Experimental and DFT Investigation.pdf


Fig. A1. Convergce tests for atomic layr nmber and cutoff energies for DFT calculations. (a) Variation of adsorption energy of chlorine with layer number, cutoff energies of  $50 / 200\mathrm{Ry}$  were applied. (b) Variation of total system energy with cutoff energies for wave function and electron density, the cutoff energy for electron density was set to be 4 times that for wave function, as a default setting in Quantum Espresso.

The line chart shows the relationship between layer number and adsorption energy, with a decreasing trend, indicating that for a certain structure adsorption is more likely.

The line chart illustrates the decrease in total energy with increasing cut-off energies.

| Layer number | Adsorption Energy (eV) |
|---|---|
| 4 | 4.2 |
| 6 | 4.13 |
| 8 | 4.12 |
| 10 | 4.12 |
| 12 | 4.12 |

| Cut-off energies (Ry) | Total energy (Ry) |
|---|---|
| 15 | -945.9 |
| 20 | -946.1 |
| 25 | -946.2 |
| 30 | -946.3 |
| 35 | -946.3 |
| 40 | -946.3 |
| 45 | -946.3 |
| 50 | -946.3 |
| 55 | -946.3 |
| 60 | -946.35 |

Answer: Energy in Ry (Rydberg) is a fundamental unit in atomic physics, representing the ionization energy of a hydrogen atom from its ground state, approximately 13.6 electron volts (eV).

Answer: 50 Ry

Answer: It could be that from a certain thickness onwards, the substrate has no repelling influence on adsorption anymore.

Answer: Layer number 8.

icdar2026-competition-data/train/atomic-layer-etching/simulation-usecase/9/Mechanism of photoassisted atomic layer etching of chlorinated Si(111) surfaces Insight.pdf


Fig. A2. Variation of the lowest excitation energy with the number of Si atoms of the cluster, insets are the molecular structures of the associated clusters.

The excitation energy of a system decreases as the number of silicon (Si) atoms increases, this is a stepwise relation as a function of the number of Si atoms.

| Number of Si atoms | Excitation energy (eV) |
|---|---|
| 0 | - |
| 3 | 4.1 |
| 7 | 3.7 |
| 11 | 3.6 |
| 15 | 3.2 |
| 24 | 3.2 |
| 34 | 3.1 |

Answer: n=34 as actual substrates used in experimental data are composed of way more atoms than depicted in this graph.

Answer: Big substrates in simulations require way more computing power than substrates with little number of atoms.

Answer: A reason could be the effect that more connected silicon atoms shift energy levels in adsorbed species to lower energies.

Answer: No this is unlikely, except for the case where the delta time is reduced to an extremely low value