Impact of Dissolved Oxygen in Dilute HF Solution on Material Etch

Kesters, Els; Iwasaki, Akihisa; Le, Quoc Toan; Holsteyns, Frank

doi:10.4028/www.scientific.net/ssp.255.251

Cited by 3 publications

(3 citation statements)

References 3 publications

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“…Immersing in 0.05% HF with saturated dissolved oxygen (DO) concentration even for a short time (60 s) already resulted in a thickness decrease of more than 5 nm of Co layer (Figure 1). As was the case with Cu [3], the etch amount was found to decrease substantially if the DO was controlled and kept as low as 30 ppb [4]. In contrast, cleaning in the SC1 lead to a significantly lower etch amount, which could be explained by the formation of a passivation layer at the surface.…”

Section: Resultsmentioning

confidence: 99%

Effect of Cleaning Chemistries on Cobalt: Surface Chemistries and Electrical Characterization

Le¹,

Kesters²,

Akanishi

et al. 2018

SSP

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The etching characteristics of ECD cobalt in different cleaning solutions were characterized using four-point probe, spectroscopic ellipsometry, and X-ray photoelectron spectroscopy. 0.05% HF solution with saturated dissolved oxygen concentration was found to result in a substantial etch of ECD cobalt (~5 nm/min). In contrast, cleaning in the SC1 1:4:100 mixture and the formulated mixture led to a significantly lower etch amount, which could be explained by the formation of a passivation layer at the surface. XPS characterization indicated the formation of a cobalt hydroxide at the surface. The electrical evaluation of the DD structure carried out after cleaning using the formulated chemical mixture and subsequent metallization showed good yield for the 22 nm Kelvin vias, testifying an efficient cleaning of the Co surface at the via bottom.

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Section: Resultsmentioning

confidence: 99%

Effect of Cleaning Chemistries on Cobalt: Surface Chemistries and Electrical Characterization

Le¹,

Kesters²,

Akanishi

et al. 2018

SSP

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“…The second step of the cycle consists of a dHF step with a controlled amount of dissolved oxygen (DO) below 50 ppb to remove the formed oxide layer. Under the DO conditions, non-oxidized copper underneath the copper oxide is not being further etched [4]. These two steps are repeated until the desired recess depth is obtained.…”

Section: Introductionmentioning

confidence: 99%

Study of Copper Surface Preparation by Sequential Atomic Layer Wet Etching and Laser Annealing Treatments

Iwasaki¹,

Akanishi²,

Mazzamuto

et al. 2017

ECS Trans.

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Atomic scale surface preparation, e.g. atomic layer etching, cleaning, local surface modifications and selective area deposition, becomes increasingly important for device scaling at sub-10 nm technology nodes in order to meet more stringent process variations and the highly selective process requirements. In the fully self-aligned via process, a topography is created by recess etching the underlying metal (copper) layer using chemical mixtures. In addition to a high compatibility with the materials exposed, one of the key requirements is to control the copper recessing such that the change in its roughness is kept at a minimum. The fundamental understanding and control of the polycrystalline surface reactions and interactions at the atomic scale are needed. In this paper, we will demonstrate the copper recess process for atomic layer wet etching (ALWE) with combination of laser thermal annealing (LTA) for surface smoothening.

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“…Diluted HF was chosen for the study as it has commonly been used for cleaning porous low-k and showed good compatibility with copper and cobalt as long as the concentration of dissolved oxygen can be reduced and controlled. 16,17 In this case, the TiN HM is expected to remain after the wet clean. In contrast to diluted HF, the formulated chemical is designed to remove the TiN hard mask together with the etch residues.…”

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confidence: 99%

Formation and Wet Removal of Organic and Titanium-Containing Residues on Patterned TiN/Porous Low-k Structure

Kesters

Holsteyns

2018

ECS J. Solid State Sci. Technol.

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The formation of the residues after patterning of a patterned metal hard mask/dielectric stack was characterized using surface-sensitive methods (attenuated total reflection-Fourier transform infrared spectroscopy and angle-resolved X-ray photoelectron spectroscopy) and scanning electron microscopy. The effect of a reducing plasma post-etch treatment (PET), aging, and moisture on the evolution of the residues was investigated. Both polymer-based (CFx) and metal-containing (TiFx) residues were identified on the exposed surface of the stack. Without the PET, the XPS data collected at different take-off angles suggested that the metal-containing residues were covered by a thin layer of polymer-based residues. The metal-containing residues were found to continue to evolve as a function of aging time if the layer of polymer-based residues was removed by the PET, making the metal hard mask in direct contact with cleanroom air. Exposing the MHM/dielectric stack to a 100% humidity environment did not induce further growing of the TiFx residues. Despite the PET only had limited removal of the TiFx-based residues, it was efficient in removing the polymer-based CFx residues, which in turn led to a better cleaning efficiency after the subsequent wet clean. The results in this study also confirmed that diluted HF dissolved TiFx-type residues and had no CFx removal capability. Although only two chemicals are shown as examples for post-etch residue removal, the type of test structure and methodology shown in this study can be applied for investigation and optimization of any other chemical mixture candidates for cleaning purpose.

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Impact of Dissolved Oxygen in Dilute HF Solution on Material Etch

Cited by 3 publications

References 3 publications

Effect of Cleaning Chemistries on Cobalt: Surface Chemistries and Electrical Characterization

Effect of Cleaning Chemistries on Cobalt: Surface Chemistries and Electrical Characterization

Study of Copper Surface Preparation by Sequential Atomic Layer Wet Etching and Laser Annealing Treatments

Formation and Wet Removal of Organic and Titanium-Containing Residues on Patterned TiN/Porous Low-k Structure

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