FIG. 10. Atomic percentages of F, O, S, and C at the etched surface from XPS as a function of ALE cycles at  $300^{\circ}\mathrm{C}$ . Lines are a guide to the eye.

The chart shows the atomic percent of O1s, C1s, F1s, and S2p elements as a function of ALE cycles

| ALE Cycles | O1s (at.%) | C1s (at.%) | F1s (at.%) | S2p (at.%) |
|---|---|---|---|---|
| 0 | 15.5 | 14.3 | 2.0 | 0.0 |
| 10 | 10.5 | 5.8 | 5.8 | 2.0 |
| 20 | 9.9 | 5.9 | 6.2 | 1.8 |
| 30 | 9.0 | 6.3 | 6.0 | 1.7 |
| 50 | 9.0 | 6.1 | 5.5 | 2.0 |
| 75 | 7.6 | 6.2 | 6.4 | 1.4 |

Answer: Both oxygen and carbon contamination decrease significantly during ALE processing. Oxygen drops from ~16 at.% to ~8 at.% while carbon decreases from ~14 at.% to ~6 at.%. Most of this reduction occurs within the first 10 ALE cycles, after which the concentrations stabilize. The continued decrease in oxygen with additional cycles reflects removal of the initially oxidized surface layer present on the as-deposited GaN film.

Answer: Fluorine increases due to residual fluorination from the SF6 plasma half-cycle used in the ALE process.

Answer: No. The sulfur content remains below 2 at.% throughout the ALE process, indicating minimal S incorporation from the SF6 plasma.

Answer: Approximately 6 at.%.

icdar2026-competition-data/train/atomic-layer-etching/simulation-usecase/27/Isotropic atomic layer etching of GaN using SF6 plasma and Al(CH3)3.pdf


FIG. 5. Saturation curves at 150 and  $300^{\circ}\mathrm{C}$  for (a)  $\mathrm{SF}_6$  plasma exposure using  $10\times 100\mathrm{ms}$  TMA exposures and (b) varied number of  $100\mathrm{ms}$  TMA pulses with a  $10\mathrm{s}$ $\mathrm{SF}_6$  plasma step, determined over 30 ALE cycles. Lines are guides for the eye.

Saturation curve for the SF6 plasma half-cycle showing EPC vs. plasma exposure time at 150°C and 300°C. Both temperatures show rapid initial increase followed by soft-saturation, reaching ~0.31 nm/cycle at 150°C and ~0.40 nm/cycle at 300°C after 10 s exposure.

Saturation curve for the TMA half-cycle showing EPC vs. number of TMA pulses at 150°C and 300°C. Clear saturation is achieved at 300°C with 4 pulses (~0.40 nm/cycle), while 150°C requires more pulses to reach saturation (~0.31 nm/cycle).

| SF₆ plasma time (s) | 300°C (nm/cycle) | 150°C (nm/cycle) |
|---|---|---|
| 0 | 0.00 | 0.00 |
| 1 | 0.26 | - |
| 2 | 0.33 | 0.16 |
| 5 | 0.38 | 0.27 |
| 10 | 0.40 | 0.31 |
| 15 | 0.40 | 0.32 |
| 30 | 0.42 | 0.35 |

| TMA pulses | 300°C (nm/cycle) | 150°C (nm/cycle) |
|---|---|---|
| 0 | 0.00 | 0.00 |
| 1 | -0.01 | - |
| 2 | 0.39 | 0.02 |
| 3 | 0.40 | - |
| 4 | 0.40 | 0.27 |
| 5 | 0.40 | 0.25 |
| 6 | - | 0.31 |
| 7 | 0.40 | - |
| 10 | 0.40 | 0.31 |

Answer: Lower temperature inhibits fluorine diffusion into the GaN, resulting in a thinner fluorinated layer and thus a lower EPC.

Answer: 10 s was chosen because the EPC increases by only 0.02 nm/cycle when extending to 30 s, which is within experimental error.

Answer: 0.40 ± 0.02 nm/cycle.

Answer: The SF6 plasma step shows soft-saturation with a gradual increase in EPC even at longer exposure times, attributed to diffusion-limited fluorination following Deal-Grove kinetics. The TMA step shows clear, sharp saturation once sufficient pulses are provided. This difference reflects the distinct mechanisms: diffusion-controlled surface modification for fluorination vs. self-limiting ligand-exchange reactions for TMA.


FIG. 7. GaN EPC as a function of table temperature. Data for  $\mathrm{Al}_2\mathrm{O}_3$  ALE using the same  $\mathrm{SF}_6$  plasma/TMA chemistry are shown from our previous work. Thermal GaN ALE with  $\mathrm{XeF}_2 / \mathrm{BCl}_3$  is also included in the plot. Lines are guides to the eye.

The chart shows the EPC (nm/cycle) of Plasma ALE GaN, Plasma ALE Al₂O₃, and Thermal ALE GaN at various temperatures. The data points are connected by lines, indicating trends over temperature

| Temperature (°C) | Plasma ALE GaN (nm/cycle) | Plasma ALE Al₂O₃ (nm/cycle) | Thermal ALE GaN (nm/cycle) |
|---|---|---|---|
| 100 | -0.01 | - | - |
| 125 | 0.21 | - | - |
| 150 | 0.33 | - | - |
| 170 | - | - | 0.02 |
| 175 | 0.35 | -0.01 | - |
| 185 | - | - | 0.03 |
| 200 | 0.36 | 0.02 | 0.05 |
| 225 | 0.37 | 0.08 | - |
| 250 | 0.39 | 0.21 | 0.06 |
| 275 | 0.40 | 0.27 | - |
| 300 | 0.43 | 0.29 | 0.07 |
| 325 | - | 0.30 | - |
| 350 | - | 0.31 | - |
| 375 | - | 0.34 | - |

Answer: Plasma ALE provides significantly higher etch rates (0.31-0.43 nm/cycle vs. ~0.07 nm/cycle for thermal ALE) and operates over a wider temperature range. This is attributed to the higher reactivity of fluorine radicals compared to thermal XeF2, enabling more effective fluorination of the GaN surface. The wider temperature window also provides greater process flexibility.

Answer: Between 150 and 200°C.

Answer: AlF3 ALD growth dominates over the ALE reaction, resulting in net film deposition instead of etching.

Answer: It increases linearly with temperature from 0.31 nm/cycle at 150°C to 0.43 nm/cycle at 300°C.


FIG. 5. The reaction energy variations (a) and the maximum reaction energies (b) obtained from the sequential etching events of routes 1-3.

The line chart illustrates the energy changes at various reaction steps for three routes (Route 1, Route 2, and Route 3). Each route shows a distinct trend in energy increase.

The bar chart compares the maximum energy achieved by three routes (Route 1, Route 2, and Route 3). Route 3 has the highest maximum energy

| Reaction Step | Route 1 (eV) | Route 2 (eV) | Route 3 (eV) |
|---|---|---|---|
| 0 | 0.0 | 0.0 | 0.0 |
| 1 | 5.4 | 4.0 | 13.0 |
| 2 | 7.8 | 11.5 | 11.0 |
| 3 | 10.8 | 13.5 | 22.0 |
| 4 | - | 20.5 | 29.0 |
| 5 | - | 22.5 | 34.0 |

| Route | Maximum Energy (eV) |
|---|---|
| Route 1 | 5.4 |
| Route 2 | 7.3 |
| Route 3 | 12.9 |

Answer: Route 1 uses squares, Route 2 uses circles, Route 3 uses triangles.

Answer: They denote the surface moiety or atom removed at that etching event in the sequence for each route.

Answer: Route 3 has the highest maximum reaction energy.

Answer: Routes 1 and 2 represent ALET on a BCl3 adsorbed surface and have much lower maximum reaction energies than route 3, which represents conventional plasma etching of pristine Al2O3. This supports the paper’s conclusion that BCl3 presorption reduces the energetic requirement for etching, which in turn can reduce the required Ar kinetic energy for effective removal. The authors also note that changing the etching event sequence can raise the maximum energy toward the conventional plasma etching level, so sequence control matters.

icdar2026-competition-data/train/atomic-layer-etching/simulation-usecase/32/Understanding time-resolved processes in atomic-layer etching of ultra-thin Al2O3 film.pdf


(a)

This figure depicts the evolution of surface-bound species on silicon under increasing HF (hydrofluoric acid) dose, showing the number density per square nanometer (Nᵢ) for unfluorinated Si and various fluorinated forms: SiF, SiF₂, and SiF₃. Initially, the surface is composed entirely of unfluorinated Si species (~28 nm⁻²), but with increasing HF exposure, the density of fluorinated species grows. SiF appears first, followed by SiF₂ and SiF₃, suggesting a stepwise fluorination mechanism. The density of each fluorinated species eventually saturates, while the total Si-related surface density remains roughly constant, indicating that fluorination modifies the surface rather than etching it away.

| Dose (HF/nm²) | Si (nm⁻²) | SiF (nm⁻²) | SiF₂ (nm⁻²) | SiF₃ (nm⁻²) |
|---------------|-----------|------------|-------------|-------------|
| 0             | 28        | 0          | 0           | 0           |
| 50            | 26        | 5          | 3           | 2           |
| 100           | 26        | 7          | 4           | 3           |
| 150           | 26        | 8          | 4           | 3           |
| 200           | 26        | 8          | 4           | 3           |

Answer: As the HF dose increases, the number density of unfluorinated surface Si atoms decreases, while the densities of fluorinated species (SiF, SiF₂, and SiF₃) increase. The total surface species density remains approximately constant, suggesting a substitutional process where fluorine atoms progressively bond with silicon to form higher fluorinated states. SiF forms first and dominates at lower doses, followed by SiF₂ and SiF₃, which appear and saturate at higher doses

Answer: Yes

Answer: SiF.

Answer: Surface fluorination proceeds in a stepwise manner, Si to SiF to SiF₂ to SiF₃, SiF is dominant at low HF doses, SiF₂ and SiF₃ emerge and saturate later

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


Figure 12. Evolution of populations of surface species  $(N_{i})$  in the modified layer as a function of HF dose. The solid lines are the results of 1D continuum model while symbols are directly obtained from MD simulations with  $E_{\mathrm{in}}$  of  $50~\mathrm{eV}$  and  $\theta_{\mathrm{in}}$  of  $0^{\circ}$ . Panel (a) depicts the population change of silicon fluoride species, namely  $\mathrm{SiF_0}$ ,  $\mathrm{SiF_1}$ ,  $\mathrm{SiF_2}$ , and  $\mathrm{SiF_3}$ . Panel (b) illustrates the changes in ammonia-derived species, specifically  $\mathrm{NH_0}$ ,  $\mathrm{NH_1}$ , and  $\mathrm{NH_2}$ . Panel (c) presents the ratio of N to Si, with the dashed line indicating the bulk stoichiometry of 1.33. (b) (c)

This figure plots the evolution of various nitrogen-containing surface species as a function of HF dose, measured in molecules per square nanometer (Nᵢ, nm⁻²). The total nitrogen concentration (N) initially drops with HF exposure, suggesting removal or conversion, but then stabilizes around 30 nm⁻². NH₀ (neutral nitrogen) shows a slight decline, while NH₁ and NH₂ exhibit clear increasing trends. This suggests that as HF dose increases, nitrogen becomes increasingly hydrogenated, forming amine-like species. The saturation of NH₁ and NH₂ levels beyond ~100 HF/nm² implies a steady-state surface composition. The figure highlights the chemical evolution of surface-bound nitrogen species during HF exposure.

| Dose (HF/nm²) | N (nm⁻²) | NH₀ (nm⁻²) | NH₁ (nm⁻²) | NH₂ (nm⁻²) |
|---------------|-----------|-------------|-------------|-------------|
| 0             | 35        | 10          | 0           | 0           |
| 50            | 30        | 8           | 5           | 2           |
| 100           | 28        | 7           | 7           | 3           |
| 150           | 30        | 7           | 9           | 4           |
| 200           | 32        | 8           | 9           | 5           |

Answer: The figure shows that atomic nitrogen (N) initially decreases in surface concentration with increasing HF dose but then plateaus, indicating partial consumption or transformation. In contrast, NH₁ and NH₂ species increase steadily with dose, suggesting progressive hydrogenation of nitrogen as HF exposure continues. NH₀ decreases slightly over time. These trends point to a surface reaction pathway where nitrogen becomes increasingly substituted with hydrogen, possibly due to HF-mediated surface reactions leading to NHₓ termination.

Answer: Yes

Answer: NH₁.

Answer: HF exposure hydrogenates nitrogen , Atomic nitrogen partially converts to NH₁ and NH₂ species, Surface nitrogen composition stabilizes beyond ~100 HF/nm².


FIG. 12. Normalized atomic Si counts as a function of  $\mathsf{Ar}^+$  fluence for various  $\mathsf{Ar}^+$  energies. Subfigure (a) shows the results for OES experiments (using the modified OES Si signals) and subfigure (b) shows results from MD ALE simulations. For both the OES and MD results, the counts are normalized using the value at the plateau observed at  $80 \text{eV}$ .

Panel (a) shows experimental measurements of Si count as a function of Ar⁺ ion dosage for three incident energies. The Si signal is consistently highest at 215 eV and increases with dosage before saturating, while the 80 eV signal shows a moderate rise and 45 eV shows negligible counts.

Panel (b) presents Monte Carlo simulation results for the same ion energies and dosages. The simulated Si counts for 215 eV also show a plateauing behavior at higher dosages, though with more fluctuations and slightly different relative magnitudes compared to the experimental data

| Ion Dosage (Ar⁺/cm²) × 10¹⁵ | 45 eV | 80 eV | 215 eV |
|----------------------------|-------|-------|--------|
| 0                          | 0     | 0     | 2      |
| 10                         | 0     | 0.5   | 4      |
| 20                         | 0     | 1     | 5      |
| 30                         | 0     | 1.5   | 6      |
| 40                         | 0     | 2     | 7      |
| 50                         | 0     | 2.5   | 8      |

| Ion Dosage (Ar⁺/cm²) × 10¹⁵ | 45 eV | 80 eV | 215 eV |
|----------------------------|-------|-------|--------|
| 0                          | 5     | 0.5   | 6      |
| 10                         | 6     | 1     | 7      |
| 20                         | 7     | 1.5   | 8      |
| 30                         | 6     | 2     | 7      |
| 40                         | 7     | 2.5   | 6      |
| 50                         | 6     | 3     | 6      |

Answer: 215 eV

Answer: Yes

Answer: More fluctuation in simulation, Clearer plateau in experiment, Smoother experimental curves with simulation error bars

Answer: between experiment and simulation allows researchers to validate modeling accuracy and adjust physical parameters like ion energy and dose for surface processing. Since 215 eV consistently leads to higher and saturating Si counts, this suggests it may be the most effective energy for maximising surface modification efficiency.

icdar2026-competition-data/train/atomic-layer-etching/simulation-usecase/6/Dynamics of plasma atomic layer etching Molecular.pdf


FIG. 13. Normalized SiCl counts as a function of  $\mathsf{Ar}^+$  fluence for various  $\mathsf{Ar}^+$  energies. Subfigure (a) shows the results for OES experiments and subfigure (b) shows results from MD ALE simulations. For both the OES and MD results, the counts are normalized using the value at the peak observed at  $80 \text{eV}$ .

The pair of scatter plots show the experimental (left) and MD-simulated (right) SiCl count as a function of Ar⁺ ion dosage for three ion energies: 45 eV, 80 eV, and 215 eV. In both cases, the SiCl count decreases with increasing dosage, with the highest initial counts observed at 215 eV. The simulation matches the trend seen experimentally, though the absolute counts differ. Error bars are shown for each data point

| Ion Dosage (Ar+/cm2) × 1015 | 45 eV | 80 eV | 215 eV |
|---|---|---|---|
| 0 | 0.75 | 0.90 | 1.60 |
| 5 | 0.60 | 0.70 | 0.80 |
| 10 | 0.55 | 0.60 | 0.70 |
| 15 | 0.50 | 0.55 | 0.60 |
| 20 | 0.45 | 0.50 | 0.55 |
| 25 | 0.40 | 0.45 | 0.50 |
| 30 | 0.35 | 0.40 | 0.45 |
| 35 | 0.30 | 0.35 | 0.40 |
| 40 | 0.25 | 0.30 | 0.35 |
| 45 | 0.20 | 0.25 | 0.30 |
| 50 | 0.15 | 0.20 | 0.25 |

| Ion Dosage (Ar+/cm2) × 1015 | 45 eV | 80 eV | 215 eV |
|---|---|---|---|
| 0 | 1.80 | 1.00 | 1.70 |
| 5 | 0.50 | 0.40 | 0.30 |
| 10 | 0.30 | 0.25 | 0.20 |
| 15 | 0.20 | 0.15 | 0.10 |
| 20 | 0.15 | 0.10 | 0.05 |
| 25 | 0.10 | 0.05 | 0.02 |
| 30 | 0.05 | 0.02 | 0.01 |
| 35 | 0.02 | 0.01 | 0.00 |
| 40 | 0.01 | 0.00 | 0.00 |
| 45 | 0.00 | 0.00 | 0.00 |
| 50 | 0.00 | 0.00 | 0.00 |

Answer: Ion dosage (Ar⁺/cm² × 10¹⁵), Ion energy (45 eV, 80 eV, 215 eV), Simulation vs. experimental conditions

Answer: Yes

Answer: 215 eV

Answer: The reduction in SiCl count with increasing ion dosage suggests a depletion of reactive surface species over time, which can lead to reduced etch efficiency or modification effectiveness during plasma processing. This implies that optimising ion energy and controlling dosage are crucial for sustaining high etch rates or achieving consistent surface functionalistion, especially in processes where product formation (like SiCl) is critical for chemical transport or material removal.


FIG. 14. Normalized  $\mathrm{SiCl}_2$  counts as a function of  $\mathsf{Ar}^+$  fluence for various  $\mathsf{Ar}^+$  energies. Subfigure (a) shows the results for OES experiments and subfigure (b) shows results from MD ALE simulations. For both the OES and MD results, the counts are normalized using the value at the peak observed at  $80\mathrm{eV}$

The experimental scatter plot shows that the SiCl₂ count decreases as ion dosage increases for all energy levels (45 eV, 80 eV, 215 eV). The highest counts are seen at 215 eV, while the lowest are at 45 eV. After ~30×10¹⁵ Ar⁺/cm², the counts plateau, indicating a saturation or steady-state regime.

The MD simulation panel reflects a similar trend to the experiment: initial steep decrease in SiCl₂ count, more prominent at higher energies. Notably, the simulated values begin at a slightly higher range than experimental values and converge more rapidly with dosage

| Ion Dosage (Ar⁺/cm²) × 10¹⁵ | 45 eV  | 80 eV  | 215 eV  |
|-----------------------------|--------|--------|---------|
| 0                           | 1.2    | 1.4    | 1.6     |
| 5                           | 0.9    | 1.1    | 1.3     |
| 10                          | 0.7    | 0.9    | 1.1     |
| ...                         | ...    | ...    | ...     |

| Ion Dosage (Ar⁺/cm²) × 10¹⁵ | 45 eV  | 80 eV  | 215 eV  |
|-----------------------------|--------|--------|---------|
| 0                           | 1.30   | 1.75   | 2.1     |
| 5                           | 0.80   | 1.20   | 1.4     |
| 10                          | 0.55   | 0.85   | 1.0     |
| 15                          | 0.45   | 0.70   | 0.85    |
| 20                          | 0.40   | 0.60   | 0.78    |
| 25                          | 0.35   | 0.55   | 0.72    |
| 30                          | 0.30   | 0.50   | 0.65    |
| 35                          | 0.28   | 0.48   | 0.60    |
| 40                          | 0.27   | 0.46   | 0.58    |
| 45                          | 0.26   | 0.45   | 0.56    |
| 50                          | 0.25   | 0.45   | 0.55    |

Answer: Ion energy transfer, Surface atom displacement, SiCl₂ formation and ejection, Yield reduction with dose

Answer: No

Answer: In both experimental and simulated datasets, the SiCl₂ count decreases with increasing ion dosage for all ion energies. The rate of decrease is steepest between 0 and 15×10¹⁵ Ar⁺/cm², after which the counts stabilize, indicating a saturation effect. Higher ion energies (e.g., 215 eV) consistently produce more SiCl₂ than lower energies like 45 eV, reflecting enhanced sputtering or reaction yields under more energetic conditions.

Answer: 215 eV


FIG. 8. Etch per cycle (EPC) in units of nm/cycle for experiments (black squares) and MD simulations (red triangles) as a function of  $\mathsf{Ar}^+$  energy. Error bars represent  $95\%$  confidence intervals.

The scatter plot compares the EPC (etching per cycle) values measured experimentally and via MD simulations across a range of ion energies. Both datasets exhibit a positive correlation between ion energy and EPC, indicating that higher ion energies lead to more effective etching. However, the experimental EPC values increase more rapidly and reach higher maximum values than those predicted by MD simulations. This suggests that simulations may underestimate etch rates due to idealised conditions, or that experimental conditions involve synergistic effects not captured in the model. The discrepancy becomes more pronounced above ~100 eV, highlighting the importance of validating simulations against experimental benchmarks

| Ion Energy (eV) | EPC (Experiments, nm/cycle) | EPC (MD Simulations, nm/cycle) |
|-----------------|-----------------------------|---------------------------------|
| 0               | 0.0                         | 0.0                             |
| 25              | 0.3                         | 0.1                             |
| 50              | 0.6                         | 0.2                             |
| 75              | 1.2                         | 0.6                             |
| 100             | 2.2                         | 1.2                             |
| 125             | 3.2                         | 1.8                             |
| 150             | 4.3                         | 2.2                             |
| 175             | 5.5                         | 2.6                             |
| 200             | 6.4                         | 3.0                             |
| 225             | 7.0                         | 3.4                             |
| 250             | 7.5                         | 3.8                             |

Answer: Both experimental and simulation results show increasing EPC with rising ion energy, indicating enhanced etching efficiency. However, the experimental data consistently show higher EPC values than the simulations, especially beyond 100 eV. This suggests either additional synergistic effects in the experiment or limitations in the simulation model, such as neglect of secondary ion effects or surface roughness.

Answer: Around 100 eV

Answer: Higher momentum transfer, Increased sputtering yield, Enhanced bond breaking, Deeper penetration for bulk removal.

Answer: Yes


The chart shows the atomic percent of O1s, C1s, F1s, and S2p elements as a function of ALE cycles.

| ALE cycles | O1s | C1s | F1s | S2p |
|---|---|---|---|---|
| 0 | 15 | 14 | 2 | 0 |
| 10 | 10 | 6 | 6 | 2 |
| 20 | 10 | 6 | 6 | 2 |
| 30 | 9 | 6 | 6 | 2 |
| 50 | 9 | 6 | 6 | 2 |
| 70 | 8 | 6 | 6 | 2 |

Answer: The ALE process removes oxygen and carbon species.

Answer: The atomic percentage together do not add up till 100%, this means that there are more species in the film not in the graph.

Answer: 30 ALE cycles are required.

Answer: It is likely that gases such as SF6 are used which remain in the film.

icdar2026-competition-data/train/atomic-layer-etching/simulation-usecase/8/Isotropic atomic layer etching of GaN using SF6 plasma and AI(CH3)3.pdf


FIG. 3. (a) Contributions of Ga-O and Ga-N to the Ga3d peak area plotted as a function of sputter depth. The vertical dashed line indicates the spectra shown in (b). (b) The Ga3d signal after  $20\mathrm{s}$  of sputtering, highlighting the positions of the Ga-O and the Ga-N peaks at  $20.5$  and  $19.3\mathrm{eV}$ , respectively.

The line chart shows the peak area of XPS signals for Ga-N and Ga-O as a function of sputter depth.

The spectrum displays the XPS counts at various binding energies for Ga-N and Ga-O.

| Sputter depth (nm)| Peak area (CPS eV) Ga-O| Peak area (CPS eV) Ga-N|
|---|---|---|
| 0 | 4000 |0|
|5|1300|4500|
|10|1000|5000|
|15|1000|5000|
|20|1000|5000|
|25|0|5700|
|30|0|6000|
|35|0|5700|
|40|0|500|

| Binding energy (eV) | XPS counts (a.u.) |
|---|---|
| 14 | 0 |
| 16 | 0 |
| 18 | 0.3 |
| 20 | 2 |
| 22 | 0.3 |
| 24 | 0 |
| 26 | 0 |

Answer: The envelope, which is a result of the two contributions together does not fully overlap with the measured spectrum indicating that the fit is not fully accurate.

Answer: Nitrogen is more present, at least in the form where it is bonded to gallium.

Answer: From 25 nm and deeper.

Answer: Depth profiles with XPS are known to influence material properties. During the sputtering binding states can change and shift, so it is possible that the film has been altered due to the measurement.


The line chart shows the relationship between SF₆ plasma time and EPC (nm/cycle) at two temperatures, 300°C and 150°C.

The line chart illustrates the relationship between TMA pulses and EPC (nm/cycle) at two temperatures, 300°C and 150°C.

| SF₆ plasma time (s) | EPC (nm/cycle) 300 degrees |EPC (nm/cycle) 150 degrees |
|---|---|---|
| 0 | 0.0 |0.0|
| 5 | 0.37 |0.27|
| 10 | 0.4 |0.3|
| 15 | 0.41 |0.31|
| 30 | 0.41 |0.35|

| TMA pulses | EPC (nm/cycle) 300 degrees |EPC (nm/cycle) 150 degrees |
|---|---|---|
| 0 | 0.4 |0.0|
| 2 | 0.4 |0.05|
| 4 | 0.4 |0.25|
| 6 | 0.4 |0.31|
| 10 | 0.4 |0.31|

Answer: The main physical parameter that is changed upon increasing the number of TMA pulses which is the partial pressure of TMA. Increasing this will increase the reaction possibility.

Answer: The maximum EPC is 0.31 nm/cycle.

Answer: It could be that the penetration depth of the radical species increases for increasing temperature.

Answer: There is no straight line for increasing plasma time, this looks like soft-saturation.


The chart shows the EPC (nm/cycle) of Plasma ALE GaN, Plasma ALE Al₂O₃, and Thermal ALE GaN at various temperatures. The data points are connected by lines, indicating trends over temperature.

| Temperature (°C) | Plasma ALE GaN | Plasma ALE Al₂O₃ | Thermal ALE GaN |
|-----------------|----------------|------------------|----------------|
| 100            | 0.0            | 0.0              | 0.0            |
| 150            | 0.2            | 0.0              | 0.0            |
| 200            | 0.3            | 0.0              | 0.05           |
| 250            | 0.4            | 0.2              | 0.1            |
| 300            | 0.4            | 0.3              | 0.1            |
| 350            | 0.4            | 0.3              | 0.1            |

Answer: Yes there is a selectivity window between 100 and 175 degrees celcius, so GaN can be etched selectively wrt Al2O3.

Answer: The plasma process yields way higher etch per cycle for lower temperatures.

Answer: Increase the temperature when etching Al2O3 instead of GaN.

Answer: 375 degrees would yield the highest EPC.