Figure 4. AFM images of  $\mathrm{Y}_2\mathrm{O}_3$  films for  $\mathrm{Y}(\mathrm{EtCp})_2(\mathrm{iPr - amd})$  with (a)  $\mathrm{H}_2\mathrm{O}$ , (b)  $\mathrm{O}_2$  plasma, and (c)  $\mathrm{H}_2\mathrm{O}$  plasma and (d) the corresponding XRR patterns.


FIG.5. Evolution of surface coverage as a function of time during a  $0.3\mathrm{s}$  dose and 1s purge. The simulations assume a precursor pressure at the inlet of  $\rho_{0} = 75\mathrm{mTorr}$ , and a reaction probability for the self-limited process  $\beta_{10} = 10^{-2}$ .

icdar2026-competition-data/train/atomic-layer-deposition/simulation-usecase/11/Angel Yanguas-Gil et al.pdf


FIG. 11. Evolution of coverage as a function of time for a self-saturating process where  $f = 0.1$  and  $\beta_{1b} = 10^{-4}$ . While the fast component reaches saturation after  $0.5 \mathrm{~s}$ , the remaining a  $10\%$  of the sites require an order of magnitude higher dose times, resulting in a homogeneous yet unsaturated profile. A fully saturated wafer from an ideal self-limited process is shown as comparison.


FIG. 14. By-product coverage at saturation on  $300\mathrm{mm}$  wafers for two different values of by-product reactivity: (a)  $\beta_{bp} = 10^{-4}$  and (b)  $\beta_{bp} = 10^{-3}$ . The precursor reactivity is  $\beta_{10} = 10^{-2}$ .


FIG. 2. Velocity profiles for our two simulation domains: (a) tube cross-flow geometry and (b)  $300\mathrm{mm}$  wafer reactor.


FIG. 6. Surface coverage for increasing dose times of 0.1, 0.2, and  $0.4 \text{s}$ . The simulations assume a precursor pressure at the inlet of  $\beta_{0} = 75 \text{mTorr}$ , and a reaction probability for the self-limited process is  $\beta_{10} = 10^{-2}$  (left) and  $\beta_{10} = 10^{-3}$  (right).


FIG. 11. (Color online) Pulse-averaged scalar concentrations  $(c / c_0)$  on the sample. The injection directions are presented by the triangle in the figure.

The figure shows a series of heatmaps for Reynolds number (Re) 40, with varying color gradients indicating intensity.

The figure shows a series of heatmaps for Reynolds number (Re) 80, with varying color gradients indicating intensity.

The figure shows a series of heatmaps for Reynolds number (Re) 200, with varying color gradients indicating intensity.

The figure shows a series of heatmaps for Reynolds number (Re) 800, with varying color gradients indicating intensity.

The figure shows a series of heatmaps for Reynolds number (Re) 2400, with varying color gradients indicating intensity.

| Re=40 | Re=80 | Re=200 | Re=800 | Re=2400 |
|---|---|---|---|---|
| ![](https://example.com/image1.png) | ![](https://example.com/image2.png) | ![](https://example.com/image3.png) | ![](https://example.com/image4.png) | ![](https://example.com/image5.png) |

| Re=40 | Re=80 | Re=200 | Re=800 | Re=2400 |
|---|---|---|---|---|
| ![](https://example.com/image6.png) | ![](https://example.com/image7.png) | ![](https://example.com/image8.png) | ![](https://example.com/image9.png) | ![](https://example.com/image10.png) |

| Re=40 | Re=80 | Re=200 | Re=800 | Re=2400 |
|---|---|---|---|---|
| ![](https://example.com/image11.png) | ![](https://example.com/image12.png) | ![](https://example.com/image13.png) | ![](https://example.com/image14.png) | ![](https://example.com/image15.png) |

| Re=40 | Re=80 | Re=200 | Re=800 | Re=2400 |
|---|---|---|---|---|
| ![](https://example.com/image16.png) | ![](https://example.com/image17.png) | ![](https://example.com/image18.png) | ![](https://example.com/image19.png) | ![](https://example.com/image20.png) |

Answer: The flow seems continuous or laminar, as the lines are relatively parallel and the transitions smooth.

Answer: In the case of CVD it is important that every part of the substrate is exposed to the same amount of flow. This also means that low Reynolds numbers work better.

Answer: It seems as if there is turbulant flow, as the boundaries are not parallel and show lots of twists.

Answer: No, it is unlikely as the gas density is higher in one part of the sample. However, still saturation can be reached everywhere, but takes a bit longer.

icdar2026-competition-data/train/atomic-layer-deposition/simulation-usecase/31/Petteri Peltonen et al.pdf


FIG. 12. (Color online) Simulated  $\lambda$  correlation for all Reynolds numbers and the measured surface thickness in the perpendicular injection configuration. The small dots in the thickness maps indicate the locations of the measurement probes while the triangles indicate the directions of the precursor sources with respect to the sample. The lower triangle indicates the TMA injection and the right triangle the injection of water. FIG. 13. (Color online) Simulated  $\lambda$  correlation and the measured surface thickness after 50 and 600 cycles in the opposing injection configuration. (a) The pulse-averaged scalar concentration for constant flow rate during the pulse (left) and  $50\%$  increased flow rate (right). (b) Streamlines on the midsection of the inlet lines during the pulse. The arrow indicates the line with increased flow rate.

Heatmaps displaying λ correlation at various Reynolds numbers (Re) ranging from 40 to 2400, for injection directions tilted 90 degrees.

Heatmaps displaying λ correlation at various Reynolds numbers (Re) ranging from 40 to 2400, for opposite injection directions.

Heatmaps displaying thickness, after 10 and 600 cycles, for injection directions tilted 90 degrees.

Heatmaps comparing measured thickness at 10 and 600 cycles, for opposite injection directions.

| Measured 10 cycles | Measured 600 cycles |
|---|---|
| ![](https://example.com/image11.png) | ![](https://example.com/image12.png) |

Answer: Re = 80

Answer: 800.

Answer: No, the non-uniformity is not constant, for 10 and for 600 cycles the high spots are at completely different locations.

Answer: Yes, the deposition is more dependent on the flow coming from the black arrow, as there a thicker layer is measured.


FIG. 14. (Color Online) Effect of increased flow rate during the pulse at  $\mathrm{Re} = 40$

The heatmap displays a gradient color scale ranging from 0.00 to 0.10, with contour lines indicating varying intensities, due to flows from the right side.

The heatmap illustrates the flow inside a scientific setup with a central point and surrounding curved lines, representing flow patterns.

| Left |Right |
|---|---|
| 0.00-0.10 |0.10|

Answer: The right image shows a better distribution over the full wafer, eventhough there is more turbulance.

Answer: There should not be, if dosed long enough the thickness should be equal everywhere.

Answer: Yes

Answer: The most prominent turbulance features are visible close to the instreames of the gases.


FIG. 5. (Color online) Instantaneous velocity fields on the midsection of the inlet pipes.

The heatmap displays the instantaneous velocity fields in the reactor for a flow with Reynolds number (Re) of 40. There is only laminar flow.

The heatmap displays the instantaneous velocity fields in the reactor for a flow with Reynolds number (Re) of 80. There is only laminar flow.

The heatmap displays the instantaneous velocity fields in the reactor for a flow with Reynolds number (Re) of 200. There are some features visible  in the middle related to turbulant flows.

The heatmap displays the instantaneous velocity fields in the reactor for a flow with Reynolds number (Re) of 800. There are features visible  in the middle related to turbulant flows.

The heatmap displays the instantaneous velocity fields in the reactor for a flow with Reynolds number (Re) of 2400. There are features visible related to turbulant flows, already from the inlet.

Answer: Yes this is bad for the reactor as it can lead to backflow of chemicals into the lines.

Answer: It could be that the flow is bounced back from the grid support, but as it can not go back into the stream it will divert into the middle.

Answer: No this does not necessarily have to be the case. As long as the exposure time is long enough to also fully cover the less dense areas.

Answer: No, only laminar flow.


FIG. 7. (Color online) Streamlines of the average velocity field at the midsection of the inlet pipes. The planes are colored by the mean velocity magnitude  $U / U_{\mathrm{in}}$


FIG. 8. (Color online) Time-averaged velocity fields  $U / U_{\mathrm{in}}$  just below the grid part of the reactor for  $\mathrm{Re} = 40$ , 800 and 2400 from left to right, respectively. (a) The time averaged value of parallel to the grid velocity component isocontour at  $\bar{u} = U_{\mathrm{in}} / 36$  for  $\mathrm{Re} = 80$  (left) and  $\mathrm{Re} = 800$  (right). (b) Turbulence intensity  $I = u_{\mathrm{rms}}^{\prime} / U_{\mathrm{in}}$  in percentages for  $\mathrm{Re} = 80$  (left) and  $\mathrm{Re} = 800$  (right) slightly above the plane where the sample lies. Note the two different color scales.


FIG. 9. (Color online) Illustrations of the grid passage modes and increase of turbulence intensity at higher Reynolds number. Fig. 10. Spatial average of a precursor on the sample as a function of time during a half-cycle. The averages are presented in four equal sized sector sectors (Q1-Q4) for all Reynolds numbers. The gray region indicates the time of the pulse and the arrow the injection direction.

The figure illustrates two modes of fluid dynamics: diffusive mode and dynamic mode. It includes a conceptual diagram of the primary and secondary jets, and heatmaps representing concentration distributions.

The line charts depict the temporal evolution of normalized concentration (c/c0) at different Reynolds numbers (Re) for four quadrants (Q1, Q2, Q3, Q4).

|Reynolds number | Graph look|
|---|---|
|40|Smooth distribution over time|
|80|Smooth distribution over time|
|200| Smooth distribution over time|
|800|Non-smooth distribution over time|
|2400|Non-smooth distribution over time|

Answer: Diffusive mode

Answer: red

Answer: The lines show peaks and dips instead of a smooth graph, indicating there is turbulance.

Answer: Q3 is seperated from the influx of species by the grid support, resulting in less direct flow. The flow in Q3 is diffused there.


Fig. 11 - Snapshots of TMA concentration profiles on the substrate surface, scales in  $\mathrm{mol} / \mathrm{m}^3$ : a)  $20\mathrm{ms}$ , b)  $30\mathrm{ms}$ , c)  $60\mathrm{ms}$ , d)  $80\mathrm{ms}$ , e)  $100\mathrm{ms}$ , f)  $200\mathrm{ms}$ , after the start of the TMA pulse.

The image gives TMA concentration profiles on the substrate surface, scales in mol/m3 after the start of the TMA pulse for 20 ms

The image gives TMA concentration profiles on the substrate surface, scales in mol/m3 after the start of the TMA pulse for 30 ms

The image gives TMA concentration profiles on the substrate surface, scales in mol/m3 after the start of the TMA pulse for 60 ms

The image gives TMA concentration profiles on the substrate surface, scales in mol/m3 after the start of the TMA pulse for 80 ms

The image gives TMA concentration profiles on the substrate surface, scales in mol/m3 after the start of the TMA pulse for 100 ms

The image gives TMA concentration profiles on the substrate surface, scales in mol/m3 after the start of the TMA pulse for 200 ms

| Value |
| --- |
| 0.0001 |
| 0.0002 |
| 0.0003 |
| 0.0004 |
| 0.0005 |
| 0.0006 |
| 0.0007 |

| Value |
| --- |
| 0.0003 |
| 0.0004 |
| 0.0005 |
| 0.0006 |
| 0.0007 |
| 0.0008 |
| 0.0009 |

| Value |
| --- |
| 500E-6 |
| 460E-6 |
| 480E-6 |
| 500E-6 |
| 520E-6 |
| 540E-6 |
| 560E-6 |
| 580E-6 |

| Value |
| --- |
| 440E-6 |
| 460E-6 |
| 480E-6 |
| 500E-6 |
| 520E-6 |
| 540E-6 |
| 560E-6 |
| 580E-6 |

| Value |
| --- |
| 380E-6 |
| 400E-6 |
| 420E-6 |
| 440E-6 |
| 460E-6 |
| 480E-6 |
| 500E-6 |
| 520E-6 |
| 540E-6 |
| 560E-6 |
| 580E-6 |

| Value |
| --- |
| 200E-6 |
| 220E-6 |
| 240E-6 |
| 260E-6 |
| 280E-6 |
| 300E-6 |
| 320E-6 |
| 340E-6 |
| 360E-6 |
| 380E-6 |
| 400E-6 |
| 420E-6 |
| 440E-6 |
| 460E-6 |
| 480E-6 |
| 500E-6 |
| 520E-6 |
| 540E-6 |
| 560E-6 |
| 580E-6 |

Answer: The loading door Ar flow purges the side of the substrate exposed to it. The loading door side of the substrate is exposed to a lower TMA concentration during the whole TMA exposure step after 60 ms from the start of the TMA pulse. The concentrations remain in the same order of magnitude as in c. The maximum concentration difference is 15.3% for d and 15.6% for e.

Answer: Yes

Answer: Yes

Answer: Notably, 20 ms after the start of the TMA pulse, the maximum concentration computed on the substrate exceeds 7 × 10−4mol/m3,while the minimum value is seven times smaller, i.e 1 × 10−4mol/m3, leading to a concentration difference of 93%. The maximum and minimum values are 9 × 10−4and 3 × 10−4mol/m3 respectively,after 30 ms.

icdar2026-competition-data/train/atomic-layer-deposition/simulation-usecase/32/reactorGP Gakis et al.pdf


Fig. 12 - Integral over time of the TMA flux on the substrate surface, scale in  $\mathrm{mol} / \mathrm{m}^2$ , during the whole TMA exposure.

The visualization shows a heatmap of TMA flux on the substrate surface, scale in mol/m2, during the whole TMA exposure integrated over time, with a color gradient indicating varying values, ranging from blue (lowest value) to red (highest value). The color bar on the right provides the scale.

| Value |
|---|
| 0.0118 |
| 0.0120 |
| 0.0122 |
| 0.0124 |
| 0.0126 |
| 0.0128 |
| 0.0130 |

Answer: In order to analyze the exposure of the substrate to TMA molecules, the species flux on the substrate surface, using the Hertz-Knudsen equation, in terms of mol/m2s is calculated. These species flux is integrated over the whole TMA exposure and purging time of the ALD cycle. The resulting exposure of the substrate to TMA molecules is plotted in the image

Answer: No

Answer: The TMA flux integral has a maximum between the substrate center and the loading door side. This corresponds to the concentration profiles on the substrate during the TMA pulse, when the re-circulation in the gas phase exists. This means that the majority of the substrate exposure to TMA occurs during the first ms of the TMA pulse.

Answer: The computed maximum exposure difference on the substrate surface during the TMA exposure is 10.7%.


Fig. 14 - Snapshots of the  $\mathbb{H}_2\mathbb{O}$  concentration profile on the substrate surface, scales in  $\mathrm{mol} / \mathrm{m}^3$ : a)  $20\mathrm{ms}$ , b)  $30\mathrm{ms}$ , c)  $60\mathrm{ms}$ , d)  $100\mathrm{ms}$ , e)  $120\mathrm{ms}$ , f)  $200\mathrm{ms}$  after the start of the  $\mathrm{H}_2\mathrm{O}$  pulse.

The heatmap images display the H2O concentration profile on the substrate surface, scales in mol/m3 for various duration after the start of the H2O pulse.

| Value |
| --- |
| 0.00032 |
| 0.00034 |
| 0.00036 |
| 0.00038 |
| 0.0004 |
| 0.00042 |
| 0.00044 |
| 0.00046 |

| Value |
| --- |
| 0.0005000 |
| 0.0005200 |
| 0.0005400 |
| 0.0005600 |
| 0.0005800 |
| 0.0006000 |
| 0.0006200 |
| 0.0006400 |
| 0.0006600 |
| 0.0006800 |

| Value |
| --- |
| 0.0007000 |
| 0.0007200 |
| 0.0007400 |
| 0.0007600 |
| 0.0007800 |
| 0.0008000 |
| 0.0008200 |

| Value |
| --- |
| 0.0006300 |
| 0.0006400 |
| 0.0006500 |
| 0.0006600 |
| 0.0006700 |
| 0.0006800 |

| Value |
| --- |
| 0.0005700 |
| 0.0005800 |
| 0.0005900 |
| 0.0005950 |

| Value |
| --- |
| 0.0003650 |
| 0.0003700 |
| 0.0003750 |
| 0.0003800 |
| 0.0003850 |

Answer:
1. Snapshot a  lead to a maximum concentration difference of 35.5%
2. Snapshot b, The maximum concentration difference is 26.6%
3. Snapshot c, the difference is 17.65%
4. Snapshot d it is 8.7%
5. Snapshot e, the maximum concentration difference is 4.5%

Answer: During the first ms of the H2O pulse, the high flow rate coming from the side inlet of the reactor suppresses the loading door purging flow, thus leading to a concentration profile with a maximum at the substrate center

Answer: From the predictions in the images, it can be concluded that during the first ms of the H2O pulse, the values of the H2O concentrations on the substrate surface are of the same order of magnitude,unlike the TMA pulse, where it took 30 ms for an almost full substrate surface exposure to TMA. It is also noted that the overall H2O concentrations are higher than in the TMA case

Answer: As the flow rate from the side inlet decreases, the loading door purge influences the species distribution, thus leading to a constantly lower H2O concentration on the loading door side of the substrate, which is exposed to the purging gas. This gradual effect is shown in b–e.


Fig. 15 - Integral over time of the  $\mathbf{H}_2\mathbf{O}$  flux on the substrate surface, during the whole  $\mathbf{H}_2\mathbf{O}$  exposure and purge, scale in  $\mathrm{mol} / \mathrm{m}^2$ .

This specific heatmap displays the integral over time of the H2O flux on the substrate surface, during the whole H2O exposure and purge, scale in mol/m2.

| Value |
|---|
| 0.038 |
| 0.0385 |
| 0.039 |
| 0.0395 |
| 0.04 |

Answer: By integrating the concentration profiles obtained after every duration, over the whole duration of the H2O exposure and purge, the total exposure is determined and shown in the figure.

Answer: The computed time integral of the species flux shows anon-uniform exposure of the substrate surface to H2O. A lower exposure is observed on the loading door side of the substrate, while a maximum is calculated on the opposite side

Answer: The maximum total exposure difference is 6.7%. This value is lower than the corresponding value for the TMA exposure

Answer: If the H2O exposure is not high enough to saturate the surface, a non-uniform film will be deposited


Fig. 6 - a) Temperature field inside the reactor chamber, b) temperature profile on the substrate surface for the substrate center at  $300^{\circ}$ C.

temperature profile on the substrate surface for the substratecenter at 300◦C.

| Object | Temperature Range (°C) |
|-----------|--------------------------|
| Reactor      | 50 – 300               |

| Object | Temperature Range (°C) |
|-----------|--------------------------|
| Substrate| 280 – 300               |

Answer: Yes

Answer: The Ar flow entering the reactor chamber at 20◦C lowers the temperature in the area close to the loading door  and at the nearby substrate side(at 279◦C). The temperature difference between the substrate center and the loading door side reads 21◦C.

Answer: The gas is quite isothermal into the reactor with a temperature close to that of the walls (270◦C), except near the inlet zones where it is colder and near the substrate where it is hotter (300◦C)

Answer: The substrate is not isothermal for image b, due to the cooling provided by the gas coming from the vicinity of the reactor walls. The calculated temperature on the substrate perimeter is equal to 289◦C.


Figure 10. Contours of the mole fraction of nitrogen on the plate rotating clockwise in R2, R3 and R4 with a gap distance of  $5\mathrm{mm}$  in the angular velocities of  $0.8$  and  $1.0\mathrm{rad / s}$ . The legend for the contours is present in Figure 9. A ring in orange denotes a nitrogen invasion into the BDEAS reaction zone, and a ring in green denotes the BDEAS runoff from the reaction zone.

Nitrogen mole fraction contour map for reactor R1 on a rotating wafer at angular velocities of 0.8 and 1.0 rad/s with a 5 mm gap, showing how reactor geometry affects nitrogen invasion and reagent runoff.

Nitrogen mole fraction contour map for reactor R2, showing noticeable intermixing at both rotation speeds.

Nitrogen mole fraction contour map for reactor R3, showing partial improvement due to asymmetric inlet placement and reduced intermixing.

| R2 | R3 | R4 |
|---|---|---|
| 0.8 (rad/s) | 0.8 (rad/s) | 0.8 (rad/s) |
| 1.0 (rad/s) | 1.0 (rad/s) | 1.0 (rad/s) |

Answer: The gap distance and angular velocity directly influence reagent separation and surface uniformity in the ASALD process. A 5-mm gap helps minimize intermixing, while angular velocities must remain below 1.0 rad/s to prevent nitrogen from entering the reaction zone and the reagent from running off. By carefully selecting these parameters and optimizing reactor design, such as using R4 with annular sector-shaped inlets, the process achieves uniform deposition and efficient separation, allowing for precise thin film thickness control and improved process performance.

Answer: Reactor R4 shows the least intermixing. Unlike R2 and R3, R4 prevents nitrogen invasion into the reaction zone at both 0.8 and 1.0 rad/s.

Answer: Yes. The text indicates that inert gas begins to invade the reaction zone when the angular wafer velocity exceeds 1.0 rad/s, and the reagent enters the purge zone above 1.2 rad/s.

Answer: Gap distance set to 5 mm to limit intermixing while balancing computational efficiency, Asymmetrical positioning of cylindrical injection ports in R3, Annular sector-shaped reagent inlets in R4, Orientation of injection ports (symmetrical or asymmetrical) optimized

icdar2026-competition-data/train/atomic-layer-deposition/simulation-usecase/38/Sungil Yun et al.pdf


Figure 12. Concentration gradient of  $\mathrm{N}_2$  mole fraction for R4 illustrating the small length scales in micrometers for each contour along the reagent-purge boundary region, which limits the availability for studying the temporal progression of surface coverage as depicted in Figure 2.

Figure 12 illustrates the concentration gradient of N₂ mole fraction along the reagent-purge boundary in reactor R4. The heatmap shows the small micrometer-scale variations in N₂ concentration, highlighting the limited spatial resolution available for capturing the temporal progression of surface coverage. These small length scales make it challenging to collect surface coverage data at high angular velocities and short time scales, which contributes to the discontinuous curves observed in Figure 11. The figure emphasizes the spatial difficulty in simulating adsorption dynamics near the boundary region.

| Position along boundary (µm)|N₂ Mole Fraction|
|-----------------------------|----------------|
|0.0|0.450|
|1.3|0.505|
|4.6|0.560|
|8.4|0.615|
|12.5|0.670|
|16.8|0.725|
|21.2|0.780|
|25.9|0.835|
|30.8|0.890|
|36.0|0.945|
|41.5|1.000|

Answer: The N₂ concentration gradient highlights the spatial limitations for collecting accurate surface coverage data along the boundary region. By understanding these small-scale gradients, researchers can adjust simulation parameters, such as time step and nodal resolution, to better capture adsorption dynamics. This insight helps explain the discontinuous curves seen in Figure 11 and guides the design of more precise ASALD simulations, ensuring accurate prediction of surface coverage and uniform film deposition under different operating conditions.

Answer: The N₂ mole fraction gradually increases from 0.450 to 1.000 along the boundary, illustrating a smooth concentration gradient across micrometer-scale positions.

Answer: Yes

Answer: Small spatial length scales (micrometers) along the reagent-purge boundary, Limited nodal data collection at these small scales, High angular velocities reducing exposure time, Constraints in temporal resolution (milliseconds) for capturing adsorption dynamics


Figure 14. Contours of (a) Nitrogen mole fraction, (b)  $\mathrm{H}_2\mathrm{O}$  mole fraction, (c) DEA mole fraction, and (d)  $\mathrm{O_2}$  mole fraction on the wafers at 2 s with  $0.4\mathrm{rad / s}$  From bottom left counter-clockwise, the wafers in the Hacac, BDEAS, and ozone reaction zones, respectively.

Nitrogen (N₂) mole fraction on wafers at 2 s and 0.4 rad/s rotation, showing spatial distribution across the wafer surfaces in the Hacac, BDEAS, and ozone reaction zones.

Water (H₂O) mole fraction on wafers at 2 s and 0.4 rad/s rotation, visualized as a heatmap showing areas of accumulation and depletion across the wafer surfaces.

DEA (C4H11N) mole fraction on wafers at 2 s and 0.4 rad/s rotation, illustrating spatial distribution across the wafer surfaces in its reaction zone.

Oxygen (O₂) mole fraction on wafers at 2 s and 0.4 rad/s rotation, visualized as a heatmap showing areas of accumulation and depletion across the wafer surfaces.

| Mole fraction of n2| |
|--------------------|---|
|1.00e+00|96.8e-01|
|9.37e-01|9.05e-01|
|8.74e-01|8.42e-01|
|8.11e-01|7.79e-01|
|7.48e-01|7.16e-01|
|6.85e-01|6.85e-01|

| Mole fraction of h2o| |
|---------------------|---|
|1.92e-05|1.73e-05|
|1.54e-05|1.34e-05|
|1.15e-05|9.60e-06|
|7.68e-06|5.76e-06|
|3.84e-06|1.92e-06|
|0.00e+00|0.00e+00|

| Mole fraction of c4h11n| |
|------------------------|---|
|4.40e-04|3.96e-04|
|3.52e-04|3.08e-04|
|2.64e-04|2.20e-04|
|1.76e-04|1.32e-04|
|8.80e-05|4.40e-05|

| Mole fraction of o2| |
|--------------------|---|
|7.33e-05|6.60e-05|
|5.87e-05|5.13e-05|
|4.40e-05|3.67e-05|
|2.93e-05|2.20e-05|
|1.47e-05|7.33e-06|
|0.00e+00|0.00e+00|

Answer: Understanding the spatial distribution of reagents on the wafers helps optimize exposure uniformity and minimize undesired intermixing. By analyzing the heatmaps, engineers can adjust rotation speeds, reagent flow rates, and reactor geometry to achieve more uniform surface coverage in each reaction zone. This ensures consistent thin-film deposition and enhances overall process efficiency, preventing areas of incomplete coverage or reagent depletion that could affect film quality.

Answer: The bottom left wafer corresponds to the Hacac reaction zone.

Answer: Yes. The heatmaps show spatial variations in mole fractions for N₂, H₂O, DEA, and O₂, indicating non-uniform distribution across the wafers.

Answer: Rotation speed of the wafer (0.4 rad/s), Type of reagent (N₂, H₂O, DEA, O₂), Reaction zone location (Hacac, BDEAS, O₃), Intermixing and diffusion effects between reagents, Temporal progression (evaluated at 2 s)


Figure 9. Contours of the mole fraction of nitrogen on the plate rotating clockwise in R2 with gap distances of  $10\mathrm{mm}$ ,  $5\mathrm{mm}$ , and  $1\mathrm{mm}$  in various angular velocities, which depict the invasion of  $\mathrm{N}_2$  into the reaction zones and reagent runoff into the purge zones at higher rotation speeds.

The figure shows nitrogen mole fraction contours on a rotating wafer in reactor R2 for three gap distances (10 mm, 5 mm, and 1 mm) under steady-state and increasing angular velocities. The contours illustrate how nitrogen penetrates the reaction zones and how reagents are dragged into the purge zones as rotation speed increases. Smaller gap distances better suppress intermixing, while higher angular velocities promote nitrogen invasion and reagent runoff, defining operational limits for maintaining self-limiting behavior.

| Gap Distance|Steady State|Low Angular Velocity|Medium Angular Velocity|High Angular Velocity|Very High Angular Velocity|
|-------------|------------|--------------------|-----------------------|---------------------|--------------------------|
|10 mm|Contours of N₂ mole fraction at steady state|0.2–0.5 rad/s|0.6–1.0 rad/s|0.7–1.2 rad/s|0.8 rad/s|
|5 mm|Contours of N₂ mole fraction at steady state|0.5 rad/s|1.0 rad/s|1.1 rad/s|1.2 rad/s|
|1 mm|Contours of N₂ mole fraction at steady state|1.0 rad/s|2.0 rad/s|2.3 rad/s|2.5 rad/s|

Answer: Minimizing nitrogen invasion is essential because intermixing disrupts the self-limiting nature of the ALD process by altering local reactant residence times and surface saturation. Excess nitrogen entering the reaction zones or reagents leaking into purge zones can reduce surface coverage uniformity, leading to nonuniform film thickness and degraded material quality. Proper control of gap distance and rotation speed helps maintain effective reagent separation, enabling high-throughput processing without compromising film uniformity.

Answer: Around 1.0 rad/s.

Answer: Yes

Answer: Gap distance between wafer and gas distribution assembly, Angular velocity of wafer rotation, Geometry of reaction and purge zones


FIG.4. AFM scan showing height-maps of TFLN waveguide sidewall with linear-planar tilt removal before (a) and after 50 ALE cycles (b) (c) Averaged AFM line scans of the TFLN waveguide side profile before and after 50 ALE cycles. The waveguide width decreases by  $50 \mathrm{nm}$  on each side, yielding a lateral etch rate of  $1 \mathrm{nm / }$  cycle, which is comparable to the vertical etch rate of  $1.59 \mathrm{nm / }$  cycle measured on bulk LN. (d) Height-map PSD of the samples before ALE and after 50 cycles of ALE.

AFM height map of the TFLN waveguide sidewall before ALE, reporting an RMS roughness (Rq) of 0.82 ± 0.25 nm.

AFM height map of the same sidewall after 50 ALE cycles, showing a reduced roughness of 0.55 ± 0.13 nm.

Averaged AFM line scans comparing the waveguide sidewall profile before and after ALE, which the caption states corresponds to a lateral etch rate of 1 nm per cycle.

PSD of the AFM height maps before and after ALE, showing lower PSD intensity after ALE across the measured spatial frequency range.

| Property | Value (nm) |
|----------|------------|
| Rq (Roughness) | 0.82 ± 0.25 |

| Property | Value (nm) |
|----------|------------|
| Rq (Roughness) | 0.55 ± 0.13 |

| Position (nm) | Height (Before ALE) | Height (After ALE) |
|---------------|---------------------|--------------------|
| 0   | ~320 | ~300 |
| 200 | ~320 | ~300 |
| 370 | ~320 | ~150 |
| 500 | ~0   | ~0   |
| 750 | ~0   | ~0   |

| Spatial Frequency (nm⁻¹) | PSD (Before ALE) | PSD  (After ALE) |
|-----------------------|--------------------|------------------|
| 0.0 | ~10³ | ~10² |
| 0.1 | ~10⁰ | ~10⁰ |
| 0.2 | ~5×10⁻¹ | ~1×10⁻¹ |
| 0.3 | ~5×10⁻² | ~1×10⁻² |
| 0.4 | ~1×10⁻² | ~8×10⁻³ |
| 0.5 | ~1×10⁻² | ~8×10⁻³ |

Answer: 0.82 ± 0.25 nm.

Answer: Yes

Answer: 1 nm per cycle.

Answer: The PSD curve after ALE is consistently lower than the curve before ALE across the full spatial frequency range shown. This reduction indicates decreased surface roughness at both low and high spatial frequencies. The trend is directly observable from the relative positions of the two curves in the plot.

icdar2026-competition-data/train/atomic-layer-etching/experimental-usecase/39/Isotropic atomic layer etching of MgO-doped lithium niobate.pdf


FIG. 6. AFM scan showing height maps of an original ALD sample (a) and after 100 ALE cycles (b). (c) Height map PSD versus spatial frequency for varying number of ALE cycles, showing a decrease in PSD intensity across all spatial frequencies with increasing number of cycles. (d) RMS roughness computed from an AFM height map against the number of ALE cycles. The dashed line is a guide to the eye.

AFM height map of original ALD-deposited TiN film (250 x 250 nm area, color scale -1 to +1 nm) showing granular surface morphology.

AFM height map after 100 ALE cycles at 300°C showing visibly smoother surface with reduced height variation.

PSD versus spatial frequency for original, 40-cycle, and 100-cycle samples. PSD decreases across all frequencies with more cycles, indicating smoothing at length scales from 2 to 20 nm.

RMS roughness versus ALE cycles, showing monotonic decrease from 4.4 Å to 2.5 Å (43% reduction) after 100 cycles.

| Spatial frequency, nm⁻¹ | Original (a.u.) | 40 cycles ALE (a.u.) | 100 cycles ALE (a.u.) |
|---|---|---|---|
| 0.05 | 6 | 5 | 4 |
| 0.1 | 2 | 1.5 | 0.8 |
| 0.15 | 0.7 | 0.4 | 0.15 |
| 0.2 | 0.3 | 0.15 | 0.05 |
| 0.3 | 0.15 | 0.08 | 0.02 |
| 0.4 | 0.12 | 0.06 | 0.015 |
| 0.5 | 0.10 | 0.05 | 0.012 |

| Number of ALE cycles | RMS roughness, Å |
|---|---|
| 0 | 4.4 |
| 20 | 3.9 |
| 40 | 3.1 |
| 60 | 2.7 |
| 80 | 2.5 |
| 100 | 2.5 |

Answer: The RMS roughness decreases monotonically from 4.4 Å to 2.5 Å after 100 cycles, a 43% reduction. The smoothing rate is fastest in early cycles and slows progressively. This is attributed to preferential etching of surface protrusions during each cycle.

Answer: The broadband PSD decrease indicates smoothing at multiple length scales (2 to 20 nm) simultaneously. This suggests the ALE process does not preferentially act on features of a particular size. Such behavior is consistent with conformal etching where oxidation and removal steps act uniformly across the surface.

Answer: The scan area is 250 x 250 nm, and the height scale ranges from -1 to +1 nm.

Answer: Rough surfaces increase the interface area where two-level systems (TLS) can form, which cause microwave loss in superconducting resonators. Reducing roughness through ALE decreases this interface area and potentially the TLS density. The 43% roughness reduction demonstrated here could improve resonator quality factors.

icdar2026-competition-data/train/atomic-layer-etching/experimental-usecase/40/Isotropic plasma-thermal atomic layer etching of.pdf


Fig. 10. Pressure contours of TMA (a) and DMAF (b) in the TMA injection region for a substrate velocity of  $80~mm / s$  and vacuum pressure of -  $100\mathrm{Pa}$  after  $1.5s$  of process filter.

A heat map displaying the pressure of TMA at various positions in the reactor.

A heat map displaying the pressure of DMAF (Dimethylamine formaldehyde)  at various positions in the reactor.

Answer: No it does not, the pressure is too low to reach the bottom of the trench.

Answer: Increase bubbler flow to have higher partial pressure of DMAF.

Answer: The 7th.

Answer: It is likely, the pressure is constant over the full depth of the trenches indicating that conformal growth can be achieved.

icdar2026-competition-data/train/atomic-layer-etching/simulation-usecase/16/Multiscale computational fluid dynamics modeling.pdf


Fig. 9. Pressure contours of HF (a) and  $\mathrm{H}_2\mathrm{O}$  (b) in the HF injection region for a substrate velocity of  $80~mm / s$  and vacuum pressure of -  $100\mathrm{Pa}$  after  $0.5s$  of process time.

Heat map showing the partial pressure of HF underneath the injector head of a spatial ALD tool, with a high pressure underneath the corresponding precursor slit.

Heat map showing the partial pressure of water underneath the injector head of a spatial ALD tool, the pressure is non-zero slightly above the surface of the substrate as water is the reaction product.

Answer: Water is the reaction product of HF with the substrate, so there is only water at the substrate and some in the purge lines.

Answer: No

Answer: This is HF that has not reacted at surface and is purged away.

Answer: There is never 100% precursor efficiency, but it seems that there is a lot of HF pumped away.


FIG. 8. AFM height maps for (a) the as-deposited  $43 \text{nm}$  thick GaN film and (b) after  $25 \text{nm}$  ALE at  $300^{\circ} \text{C}$  using the standard recipe shown in Fig. 2.

AFM height map (1×1 μm²) of the as-deposited 43 nm GaN film showing a rough surface with distinct crystalline grains. Height variations span approximately ±6 nm, with sharp peaks and valleys indicating polycrystalline morphology. RMS roughness is 2.6 ± 0.1 nm.

AFM height map (1×1 μm²) of the same GaN film after 25 nm of ALE at 300°C. The surface appears visibly smoother with reduced crystallite height and density. RMS roughness decreased to 1.9 ± 0.1 nm.

Answer: The polycrystalline nature of the ALD-grown GaN film, with individual crystalline grains creating peaks and valleys.

Answer: 1×1 μm².

Answer: Smoother interfaces reduce carrier scattering and improve electron mobility, enhancing final device performance.

Answer: The ALE process reduces both the height and density of crystalline surface features. The as-deposited film shows sharp peaks and valleys from polycrystalline GaN grains, while after 25 nm of ALE, the surface becomes visibly smoother with less pronounced height variations. The RMS roughness decreases from 2.6 ± 0.1 nm to 1.9 ± 0.1 nm, demonstrating the smoothing capability of the ALE process.

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


The figure shows an AFM image with a color gradient indicating height in nanometers. The x-axis represents the horizontal position in micrometers, and the y-axis represents the vertical position in micrometers.

The figure shows an AFM with a color gradient indicating height in nanometers. The x-axis represents the horizontal position in micrometers, and the y-axis represents the vertical position in micrometers.

Answer: The surface shows less extremes (high and low points), in addition the figure looks a bit more blurry. This indicates that the surface is less rough.

Answer: Yes, there are still high spots present.

Answer: The biggest height difference is around 13 nm, these can be called pinholes.

Answer: In most cases etching process are more affective on upstanding features, resulting in the reduction of extreme height differences.

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