Figure 7. AFM image  $(10\times 10\mu \mathrm{m}^2)$  used to determine the thickness of an  $\mathrm{Al}_2\mathrm{O}_3$  ALD film grown at  $58^{\circ}C$  using 300 ALD cycles on a Si(100) substrate. The step was created by masking part of the sample with aluminum tape during  $\mathrm{Al}_2\mathrm{O}_3$  ALD. The average step height is  $43~\mathrm{nm}$ .


FIG. 17. Cross-sectional high-resolution transmission electron microscopy (HRTEM) images of as-grown  $\mathrm{HfO_2}$  films deposited by (a) remote-plasma ALD and (b) direct-plasma ALD (Refs. 124, 125). The films were deposited on Si at a deposition temperature of  $250^{\circ}\mathrm{C}$  using  $\mathrm{Hf(NEt_2)_4}$  as the precursor and an  $\mathrm{O_2}$  plasma as the reactant. A gradual transition from the interface layer to the  $\mathrm{HfO_2}$  layer can be observed for the remote-plasma ALD film, whereas the film deposited using a direct-plasma also has an abrupt transition. The film deposited using a direct-plasma was partially crystallized, whereas using a remote-plasma afforded an amorphous film. From J. Kim et al., Appl. Phys. Lett. 87, 53108 (2005). Reprinted with permission. Copyright 2005, American Institute of Physics.

icdar2026-competition-data/test/gold_standard_test_set/atomic-layer-deposition/experimental-usecase/10/H. B. Profijt et al.pdf


FIG. 3. AFM images of surface morphology for (a)  $700^{\circ}\mathrm{C}$  annealed  $\mathrm{TiO_2 / Si}$  b  $800^{\circ}\mathrm{C}$  annealed  $\mathrm{Ta}_2\mathrm{O}_5 / \mathrm{Si}$  cBST  $\mathrm{TiO_2 / Si}$  and d  $\mathrm{BST / Ta}_2\mathrm{O}_5 / \mathrm{Si}$  structures.


Fig. 3 Representative scanning electron microscope images of  $\mathrm{ZrO_2}$  thin films from  $(\mathrm{CpMe})_2\mathrm{Zr(OMe)Me / O_3}$  and  $(\mathrm{CpMe})_2\mathrm{ZrMe}_2 / \mathrm{O}_3$  grown into deep trenches with aspect ratio  $\sim 60:1$ . The upper images show the top part of the trenches (opening diameter  $115~\mathrm{nm}$ ), those below the middle and the bottom parts to a depth of  $6.75\mu \mathrm{m}$ .  $\mathrm{ZrO_2}$  film thicknesses are denoted by labels.


Fig. 4 Transmission electron microscopy images of  $\mathrm{ZrO_2}$  thin films grown from  $(\mathrm{CpMe})_2\mathrm{Zr(OMe)Me}$  and  $(\mathrm{CpMe})_2\mathrm{ZrMe}_2$ . Growth temperatures and the number of deposition cycles are indicated by labels. Interface layer is denoted by IL.


Fig. 9 AFM images of a  $100\mathrm{-nm}$  thick LLT film deposited at  $225^{\circ}\mathrm{C}$  on silicon.


Fig. 8 (a) High resolution SEM pictures showing the surface topography and (b) cross-section of  $\mathrm{Li_2CO_3}$  deposited with plasma ALD at 50, 150, and  $250^{\circ}\mathrm{C}$ . The scale bar applies to all of the pictures.

The image shows a series of microscopic images at different temperatures (50°C, 150°C, 250°C) depicting the surface topography

The image shows a series of microscopic images at different temperatures (50°C, 150°C, 250°C) and their cross-sectional views

Answer: The film growth, and resulting topography, change drastically when increasing temperature.

Answer: Although for lower deposition temperatures highly uniform films are formed, at 250 °C, the films show large thickness variations. We expect that this is related to the combustion of organic ligands and the formation of LiOH/Li2O during deposition induced by the O2 plasma.

Answer: The scale bar 100 nm applies to all of the SEM images.

Answer: No


Fig. 9 Examination of the conformality of the  $\mathrm{Li_2CO_3}$  processes at  $150^{\circ}\mathrm{C}$ . Micropillars of  $50\mu \mathrm{m}$  high and a diameter of  $2\mu \mathrm{m}$  are used for this purpose. The pillars are coated with a  $30~\mathrm{nm}$  TiN layer on top of which a  $\sim 50 \mathrm{nm}$  layer of  $\mathrm{Li_2CO_3}$  was deposited. Images (a), (b) and (c) show the  $\mathrm{Li_2CO_3 / TiN}$  layer at respectively the top, middle and bottom of the pillars. Thickness variations from  $40 - 55 \mathrm{nm}$  (plasma) and  $48 - 60 \mathrm{nm}$  (thermal) were observed. For the thermal process a lithium dosing time of  $10 \mathrm{s}$  was used, whereas for the plasma process the standard dose time of  $6 \mathrm{s}$  was sufficient. The scale bar applies to all of the pictures.


icdar2026-competition-data/test/gold_standard_test_set/atomic-layer-deposition/experimental-usecase/23/David J. Comstock et al.pdf


Figure 8. SEM images of  $800\mathrm{~\AA~}$ $\mathrm{Ga}_{2}\mathrm{O}_{3}$  film deposited onto high-aspect ratio silicon trenches to assess the conformality of the ALD process: (a) overview of trench structure, (b) top corner of trench with  $800\mathrm{~\AA~}$ $\mathrm{Ga}_{2}\mathrm{O}_{3}$  thickness, and (c) bottom of trench with  $550\mathrm{~\AA~}$ $\mathrm{Ga}_{2}\mathrm{O}_{3}$  thickness.


Figure 4. SEM images of uncoated (left) and coated (right) high-aspect-ratio holes. The white bar in the bottom of each image measures  $100~\mathrm{nm}$


FIG. 5. (Color online) (a) Cross-sectional TEM image of a  $\sim 32\mathrm{nm}\mathrm{HfO}_2$  film deposited at  $400^{\circ}\mathrm{C}$  on a H-terminated Si substrate. The  $\mathrm{Si / HfO_2}$ $(32\mathrm{nm}) / \mathrm{SiO_x}$ $(\sim 100\mathrm{nm})$  stack demonstrating a sharp interface between  $\mathrm{HfO_2}$  and underlying Si has been highlighted within a square. (b) A close up of the cross-sectional TEM image clearly showing the individual crystalline grains of  $\mathrm{HfO_2}$  and an amorphous  $\mathrm{SiO_2}$  layer at the  $\mathrm{Si - HfO_2}$  interface.


FIG. 7. (Color online) (Left) Cross-sectional transmission electron microscopy image of a conformal  $\mathrm{HfO_2}$  layer deposited on high aspect ratio nanostructures by ALD at  $250^{\circ}\mathrm{C}$  using  $\mathrm{HfCp(NMe_2)_3}$  and  $\mathrm{O_2}$  plasma. (Right) A close up of trench structures with varying aspect ratios shows the conformal  $\mathrm{HfO_2}$  thin film.


FIG. 8. SEM images of a  $46\mathrm{nm}$ $\mathrm{SnO_x}$  film deposited on  $\mathrm{Si(100)}$  at  $150^{\circ}\mathrm{C}$  (a) as-deposited; (b) post-  $500^{\circ}\mathrm{C}$  anneal; (c) post-  $600^{\circ}\mathrm{C}$  anneal; (d) cross-section of film post-  $600^{\circ}\mathrm{C}$  anneal. The scale bars are  $300\mathrm{nm}$ .


Figure 5. (a,b) Cross-sectional TEM images of a Co film deposited by performing 1000 ALD cycles of the  $\mathrm{AB - NH_3}$  process.


Figure 4. RSA simulation results for aniline adsorption on  $\left(\mathbf{a} - \mathbf{c}\right)$ $\mathrm{Ru(0001)}$  and  $(\mathrm{d} - \mathrm{f})$ $\mathrm{Co(0001)}$  surfaces: (a and d) visual simulation output, (b and e) surface aniline configuration densities as a function of the total aniline density on the surface, and (c and f) distribution of effective gap sizes after aniline adsorption. The blue dashed line at  $0.49 \mathrm{nm}$  represents the size of the TDMAT precursor. The inset in panel c shows the procedure of determining the gap sizes by measuring the minimum distance between an unoccupied site and the nearest adsorbed inhibitor molecules (i.e., the radius of the largest circular molecule that can adsorb on the unoccupied site).

shows a visual RSA simulation snapshot of aniline molecules adsorbed on Ru(0001). Horizontal and vertical configurations populate the surface, illustrating steric blocking and coverage patterns as packing approaches saturation.

plots horizontal, vertical, and total aniline configuration densities as a function of attempted total density. Ru shows high achievable coverage, with a saturation point near ~1.8 nm⁻². Horizontal adsorption becomes dominant at high densities.

displays a histogram of effective gap sizes remaining after aniline adsorption. Ru leaves only very small gaps (<0.25 nm), far below the required TDMAT precursor radius (0.49 nm), indicating strong inhibition capability. The inset illustrates how gap sizes are measured.

shows RSA adsorption on Co(0001). The packing is visibly less dense than Ru, with more irregular spacing and larger void areas.

indicates lower total achievable density than Ru. Horizontal coverage rises but saturates earlier, suggesting less efficient packing and weaker inhibitor blocking.

shows much larger residual gaps on Co compared to Ru. Some gaps approach or exceed the TDMAT radius, meaning TDMAT could still adsorb through voids—indicating poorer blocking performance.

| Total density (nm²) | Configuration density (nm²) |
|---|---|
| 0.0 | 0.0 |
| 0.2 | 0.2 |
| 0.4 | 0.4 |
| 0.6 | 0.6 |
| 0.8 | 0.8 |
| 1.0 | 1.0 |
| 1.2 | 1.2 |
| 1.4 | 1.4 |
| 1.6 | 1.6 |
| 1.8 | 1.8 |
| 2.0 | 2.0 |

| Effective gap size (nm) | Surface density (nm⁻²) |
|---|---|
| 0.20 | 0.07 |
| 0.25 | 0.03 |
| 0.30 | 0.01 |
| 0.35 | 0.00 |
| 0.40 | 0.00 |
| 0.45 | 0.00 |
| 0.50 | 0.00 |

| Effective gap size (nm) | Surface density (nm⁻²) |
|---|---|
| 0.20 | 0.09 |
| 0.25 | 0.01 |
| 0.30 | 0.00 |
| 0.35 | 0.00 |
| 0.40 | 0.00 |
| 0.45 | 0.00 |
| 0.50 | 0.00 |

Answer: The gap-size distribution quantifies the openings left between adsorbed inhibitor molecules. If these gaps are smaller than the critical precursor radius, the precursor cannot reach the metal surface and adsorption is blocked. Ru shows mostly sub-0.25 nm gaps, far below the TDMAT effective radius, indicating strong growth inhibition. Co exhibits larger gaps, meaning the precursor may still access the surface, reducing selectivity. Thus, gap statistics directly determine how effectively an inhibitor layer prevents undesired precursor adsorption.

Answer: Ru achieves the higher packing density.

Answer: Yes — RSA places molecules one by one and stops once further insertions are sterically blocked.

Answer: Molecular orientation (horizontal vs. vertical), Packing efficiency of adsorbed molecules, Surface-dependent steric constraints, Local arrangement of nearest-neighbor molecules, Minimum distance rules used in RSA gap-size calculations


Figure 2. SEM and AFM images showing the  $\mathrm{Al}_2\mathrm{O}_3$  coverage on graphene after 100 cycles of  $\mathrm{Al}_2\mathrm{O}_3$  ALD at  $100^{\circ}\mathrm{C}$  for  $\mathbf{a},\mathbf{d}$  pristine,  $\mathbf{b},\mathbf{e}$ $30~\mathrm{s}~\mathrm{O}_2$  plasma, and  $\mathbb{C},\mathbb{f})$ $35~\mathrm{s}~\mathrm{H}_2$  plasma treated graphene. The root-mean-square (RMS) roughness determined from the AFM measurements is indicated as well.

SEM image after 100 cycles of Al2O3 ALD on pristine graphene, showing non uniform coverage with visible holes and a granular film texture.

SEM image after 100 cycles of Al2O3 ALD on graphene treated with 30 s O2 plasma, showing uniform Al2O3 coverage without visible pinholes.

SEM image after 100 cycles of Al2O3 ALD on graphene treated with 35 s H2 plasma, showing uniform Al2O3 coverage without visible pinholes.

AFM height image after 100 cycles of Al2O3 ALD on pristine graphene, showing a rough granular surface with RMS roughness 1.9 nm.

AFM height image after 100 cycles of Al2O3 ALD on 30 s O2 plasma treated graphene, showing a smooth surface with RMS roughness 0.39 nm.

AFM height image after 100 cycles of Al2O3 ALD on 35 s H2 plasma treated graphene, showing a smooth surface with RMS roughness 0.45 nm.

Answer: The much lower roughness for the O2 and H2 plasma treated samples is consistent with a closed, more continuous Al2O3 layer forming during ALD. The paper links this to plasma created surface groups that increase adsorption of the ALD precursor on graphene, which reduces the nucleation delay and improves coverage. In contrast, pristine graphene lacks sufficient adsorption sites, so nucleation is sparse and the film remains granular with holes.

Answer: It indicates that the white bar corresponds to a lateral distance of 200 nm in the image.

Answer: A closed Al2O3 layer is required if the film is to act as an effective dielectric and barrier layer on graphene. The figure shows that without pretreatment the Al2O3 is not closed, which the paper notes is not suitable for applications such as a gate dielectric. With O2 or H2 plasma pretreatment, the uniform and smooth Al2O3 indicates a much more viable dielectric layer for device integration.

Answer:
Pristine graphene: non uniform growth with holes and a granular structure, and higher RMS roughness around 1.9 nm.

O2 plasma and H2 plasma: uniform deposition with no visible pinholes, and much lower RMS roughness around 0.39 nm and 0.45 nm.

icdar2026-competition-data/test/gold_standard_test_set/atomic-layer-deposition/simulation-usecase/33/René H. J. Vervuurt et al.pdf


Figure 3. Cross-sectional TEM image of 100 cycles of  $\mathrm{Al}_2\mathrm{O}_3$  deposited on graphene treated with  $35~\mathrm{s}$ $\mathrm{H}_{2}$  plasma. The  $\mathrm{Al}_2\mathrm{O}_3$  layer is  $7.8\pm 0.4$  nm thick and pinhole-free.

Cross section TEM image of a Au capped Al2O3 graphene SiO2 stack after 100 cycles of Al2O3 ALD on graphene treated with 35 s H2 plasma, showing a uniform Al2O3 layer that is 7.8 ± 0.4 nm thick and described as pinhole free.

Answer: It corresponds to graphene treated with 35 s H2 plasma followed by 100 cycles of Al2O3 ALD.

Answer: The TEM cross section gives an Al2O3 thickness of 7.8 ± 0.4 nm. The paper reports a thickness of 9 ± 1 nm from spectroscopic ellipsometry for Al2O3 grown on H2 plasma treated graphene, and states that the TEM value is in agreement with the ellipsometry thickness within uncertainty.

Answer:
Au

, Al2O3

, Graphene

, SiO2

Answer: A uniform, pinhole free Al2O3 film is needed to function as a continuous dielectric and barrier layer rather than leaving exposed graphene regions that can leak or short. This figure is used as confirmation that, after H2 plasma functionalization and 100 ALD cycles, the Al2O3 is closed and continuous, supporting the paper’s goal of enabling practical dielectric integration on graphene.


Figure 4. a) SEM image of pristine graphene after transfer to  $\mathrm{SiO}_{2}$  and anneal at  $400^{\circ}\mathrm{C}$ . Wrinkles and bilayer graphene are visible in the image. b) SEM image of pristine graphene after 500 cycles of Pt ALD at  $300^{\circ}\mathrm{C}$ . Preferential Pt growth occurs on the graphene wrinkles, grain boundaries, and defects sites.

icdar2026-competition-data/test/gold_standard_test_set/atomic-layer-deposition/simulation-usecase/34/René H. J. Vervuurt et al.pdf


Figure 5. SEM image of graphene exposed to different plasma treatments followed by 500 cycles of Pt ALD: a)  $\mathsf{H}_{2}$  plasma 2 min, b)  $\mathsf{H}_{2}$  Plasma 4 min, c)  $\mathsf{H}_{2}$  Plasma 5 min, d)  $\Omega_{2}$  plasma 1 min, e)  $\Omega_{2}$  plasma 3 min, and f)  $\Omega_{2}$  plasma 5 min. The Pt surface coverage increases as a function of the plasma exposure time for both  $\mathsf{H}_{2}$  and  $\Omega_{2}$  plasma treatments. d-f) Adapted with permission.[19] Copyright 2016, Royal Society of Chemistry.


Figure 6. Optical micrograph of a), c) graphene patterned with CTLM structures by photolithography using photosensitive polyimide as the resist and the same structures b), d) after  $5\min$  of  $\mathsf{H}_{2}$  plasma functionalization and 1000 cycles of Pt ALD. No Pt growth occurs on the polyimide allowing for the AS-ALD of Pt. The parameters of Equation (1) are indicated in d) as well.


FIG. 5. Cross-sectional TEM images of  $\mathrm{Al_2O_3}$  deposited and etched on 3D Si trench structures. (a) Trench structure coated with an  $\mathrm{Al_2O_3}$  film by plasma ALD, showing average film thickness in four regions. (b) A similar trench structure after 40 ALE cycles, in which the thickness etched in each region is highlighted. The standard ALE cycle was used to perform the etching.

The image shows a cross-sectional view of the material structure before etching, displaying the average film thickness in four sections.

The image shows a cross-sectional view of the material structure after 40 cycles of ALE (Atomic Layer Etching), displaying changes in film thickness for four regions.

Answer: Isotropic atomic layer etching

Answer: 11.6 nm (corresponds to the difference between 23.3 nm and 11.9 nm).

Answer: No

Answer: The thickness decreases after 40 cycles of atomic layer etching (ALE).

Answer: The EPC is around 12/40 = 0.3 nm/cycle.

Answer: Especially ions within a plasma are directionall meaning that side walls in 3D structures have a lower ion dose meaning that the method is not conformal.

Answer: Al₂O₃ is removed with exceptional uniformity across the entire trench. The etched thickness ranges from ~10.4 to ~11.4 nm between the top, sidewalls, and bottom. This corresponds to a variation of less than ±5 %, demonstrating that both ALE half-reactions fully saturate all surfaces independent of aspect ratio.

Answer: ~2.66 Å/cycle in the trench versus ~3.1 Å/cycle on blanket films.

Answer: Yes

Answer: The average etch rate over the 3D trench structures was calculated to be 2.9 ± 0.1 Å/cycle, which agrees well with the Etch Per Cycle (EPC) value obtained for blanket substrates.

Answer: 40 cycles of alternating SF₆ plasma and TMA pulses.

Answer:
1. Average thickness of Al2O3 before etching = 22.6 nm
2. Average thickness of Al2O3 after 40 cycles of etching = 11.6nm

Answer: Etched thickness = 11nm, Etch rate = 11/40 = - 0.28 nm/ALE cycle.

Answer: The sidewall thickness decreases significantly after 40 ALE cycles. Pre-etch measurements ranged from 21.6 nm to 23.3 nm, while post-etch values range from 11.2 nm to 12.2 nm. This consistent reduction across the measured points suggests uniform and controlled material removal via ALE.

Answer: Pre-ALE (plasma ALD): 21.8 nm, 23.3 nm, 22.6 nm, 21.6 nm, Post 40 ALE cycles: 11.4 nm, 11.9 nm, 12.2 nm, 11.2 nm, Observation: The etch depth is relatively consistent across regions, indicating isotropic etching

Answer: Yes. The similar etch depth across different surfaces indicates that the ALE process is isotropic, meaning it does not depend strongly on the orientation of the surface.

Answer: Achieving isotropic etching ensures uniform material removal across complex 3D geometries, which is critical for maintaining structural integrity and predictable etch rates in microfabrication and semiconductor applications.

Answer: Not all measurements along the trench show the same thickness where the biggest difference is 1.7 nm, so not fully conformal.

Answer: The main reason for this difference is the different densities of the materials.

Answer: Thickness variation is less than ±0.85 nm from top to bottom of the trench.

Answer: The comparison demonstrates that the process is highly isotropic. In the pre-etch image (a), the film is conformal with a thickness of ~22 nm. After 40 cycles (b), the thickness is reduced to ~11–12 nm on both the horizontal surfaces (top/bottom) and the vertical sidewalls. The fact that the amount of material removed (~10–11 nm) is virtually identical on all faces confirms that the plasma-generated radicals etch all exposed surfaces equally, unlike ion-driven plasma processes which are typically directional.

Answer: No

Answer: Yes

Answer:
This  plasma ALE process exhibits a comparable etch depth for both horizontal and vertical surfaces of 11.4 nm and 11. 9 nm, respectively.
Anisotropic etching would lead to a higher etch rate on horizontal surfaces.  This suggests that directional ions in the SF6 plasma do not significantly contribute to etching of the Al2O3 surface. A possible explanation for why the etch rate on the horizontal surfaces appears slightly lower than that on the vertical surfaces is densification of the film due to ion exposure during the O2 plasma steps of the Al2O3 ALD cycle.

Answer: Plasma-enhanced atomic layer etching (ALE) using SF₆ plasma and TMA exposure.

Answer: Etch rate, Uniformity, Precision, Material selectivity

Answer: Yes

Answer: The Al2O3 film was first deposited on the Si trench structures using plasma ALD with TMA and O2 plasma, resulting in a uniform thickness of ~210 Å. Subsequently, the film was etched using 40 ALE cycles, which alternated SF6 plasma exposure with TMA dosing. This process led to a uniform etch across horizontal and vertical surfaces, demonstrating the isotropic nature of the ALE process.

icdar2026-competition-data/test/gold_standard_test_set/atomic-layer-etching/experimental-usecase/12/Isotropic plasma atomic layer etching of Al2O3 using a fluorine containing plasma and Al(CH3)3.pdf


FIG. 8. TEM cross sections of a  $4 \times 50 \mathrm{nm}$  InGaAs nanowire covered by  $4.7 \mathrm{nm}$  ALD-grown  $\mathrm{Al}_2\mathrm{O}_3$  and  $20 \mathrm{nm}$  of ALD tungsten. Reprinted with permission from Lu et al., in International Electron Devices Meeting, San Francisco, 1-5 December 2018 (IEDM, Montgomery Village, 2018), p. 895. Copyright 2018, IEEE.

icdar2026-competition-data/test/gold_standard_test_set/atomic-layer-etching/experimental-usecase/18/Thermal atomic layer etching A review.pdf


FIG. 10. (a) Cross-sectional TEM and (b) TEM-EDS mapping of 10 ALD/ALE super-cycles at  $270~\mathrm{ms}$  dosing conditions on  $\mathrm{Si / SiO_2}$  pattern. (c) Cross-sectional TEM and (d) TEM-EDS mapping of 30 ALD/ALE super-cycles at  $90~\mathrm{ms}$  dosing conditions on  $\mathrm{Si / SiO_2}$  pattern.

icdar2026-competition-data/test/gold_standard_test_set/atomic-layer-etching/experimental-usecase/37/Effect of reactant dosing on selectivity during area-selective.pdf


FIG. 9. SEM images of  $\mathrm{TiO_2}$  ALD/ALE on patterned  $\mathrm{Si / SiO_2}$  substrates using (a)  $270~\mathrm{ms}$  dosing conditions for 10 super-cycles and (b)  $90~\mathrm{ms}$  dosing conditions for 30 super-cycles.


FIG. 11. SEM image of (a) the film left over from fully etched Mo films (after 1000 cycles of  $\mathrm{NbCl}_5$  and  $\mathrm{O}_2$  at  $300^{\circ}\mathrm{C}$ ) and (b) after cleaning the sample with  $\mathrm{O}_3$  at  $300^{\circ}\mathrm{C}$ . AFM images of the fully etched Mo sample (c) before and (d) after cleaning with  $\mathrm{O}_3$  at  $300^{\circ}\mathrm{C}$ .

icdar2026-competition-data/test/gold_standard_test_set/atomic-layer-etching/experimental-usecase/47/Atomic layer etching of molybdenum with O2 and NbCl5.pdf


FIG. 9. SEM images of (a) an unetched molybdenum film and (b) a film etched for 200 cycles at  $300^{\circ}\mathrm{C}$  with a remaining thickness of  $41.6\mathrm{nm}$ .


Figure 7. Examples of the ALE smoothing effect. Images show the surface before and after ALE in (a) tilt SEM with Ru ALE, 100 cycles and (b) side-view HR-TEM with Si ALE, 50 cycles.

The tilt-SEM images show that Ru surface roughness decreases from 0.80 nm to 0.20 nm after 100 ALE cycles, indicating strong planarization under layer-by-layer removal conditions.

The side-view HR-TEM images of Si show pronounced smoothing after 50 ALE cycles, with reduced atomic-scale height variations at the surface compared to the incoming interface.

Answer: Each ALE cycle consists of a self-limiting surface modification step followed by a directional activation step that removes only the modified layer. On Ru, protruding features experience higher reaction probability during modification, making them preferentially removed during activation. Recessed regions remain protected because modification saturates uniformly. Repeating this cycle progressively suppresses height gradients, producing the observed reduction from 0.80 nm to 0.20 nm RMS.

Answer: A smoother Ru surface promotes uniform nucleation during subsequent barrier or liner deposition, reducing the likelihood of discontinuities. It also minimizes local electric-field and current-density concentrations that can degrade reliability. As a result, ALE-induced smoothing supports improved manufacturability and performance in advanced interconnect schemes.

Answer: 50 cycles.

Answer: ALE preferentially removes protruding lattice features, producing a more uniform near-surface atomic structure.

icdar2026-competition-data/test/gold_standard_test_set/atomic-layer-etching/simulation-usecase/21/Review Paper -- Atomic Layer Etching Rethinking the Art of Etch.pdf