A novel x-ray photoelectron spectroscopy study of the Al/SiO2 interface

Hecht, M. H.; Vasquez, R. P.; Grunthaner, F. J.; Zamani, N.; Maserjian, J.

doi:10.1063/1.335266

Cited by 36 publications

(11 citation statements)

References 26 publications

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“…Previous studies have also investigated the reaction of Al with SiO 2 . − Aluminum films deposited on thermally grown SiO 2 surfaces have been shown to reduce SiO 2 and yield Al 2 O 3 and Si according to This reaction is thermodynamically favorable with a Gibbs free energy value of Δ G = −68 kcal/mol at 300 °C . There are similarities between the reactions of TMA and Al with SiO 2 .…”

Section: Resultsmentioning

confidence: 99%

Thermal Atomic Layer Etching of SiO₂ by a “Conversion-Etch” Mechanism Using Sequential Reactions of Trimethylaluminum and Hydrogen Fluoride

DuMont

Marquardt

Cano

et al. 2017

ACS Appl. Mater. Interfaces

116

142

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The thermal atomic layer etching (ALE) of SiO was performed using sequential reactions of trimethylaluminum (TMA) and hydrogen fluoride (HF) at 300 °C. Ex situ X-ray reflectivity (XRR) measurements revealed that the etch rate during SiO ALE was dependent on reactant pressure. SiO etch rates of 0.027, 0.15, 0.20, and 0.31 Å/cycle were observed at static reactant pressures of 0.1, 0.5, 1.0, and 4.0 Torr, respectively. Ex situ spectroscopic ellipsometry (SE) measurements were in agreement with these etch rates versus reactant pressure. In situ Fourier transform infrared (FTIR) spectroscopy investigations also observed SiO etching that was dependent on the static reactant pressures. The FTIR studies showed that the TMA and HF reactions displayed self-limiting behavior at the various reactant pressures. In addition, the FTIR spectra revealed that an AlO/aluminosilicate intermediate was present after the TMA exposures. The AlO/aluminosilicate intermediate is consistent with a "conversion-etch" mechanism where SiO is converted by TMA to AlO, aluminosilicates, and reduced silicon species following a family of reactions represented by 3SiO + 4Al(CH) → 2AlO + 3Si(CH). Ex situ X-ray photoelectron spectroscopy (XPS) studies confirmed the reduction of silicon species after TMA exposures. Following the conversion reactions, HF can fluorinate the AlO and aluminosilicates to species such as AlF and SiOF. Subsequently, TMA can remove the AlF and SiOF species by ligand-exchange transmetalation reactions and then convert additional SiO to AlO. The pressure-dependent conversion reaction of SiO to AlO and aluminosilicates by TMA is critical for thermal SiO ALE. The "conversion-etch" mechanism may also provide pathways for additional materials to be etched using thermal ALE.

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Section: Resultsmentioning

confidence: 99%

Thermal Atomic Layer Etching of SiO₂ by a “Conversion-Etch” Mechanism Using Sequential Reactions of Trimethylaluminum and Hydrogen Fluoride

DuMont

Marquardt

Cano

et al. 2017

ACS Appl. Mater. Interfaces

116

142

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“…In this analysis, as well, the optical properties of Al 2 O 3 were assigned for the dielectric layer. The procedure was guided by the results of a previous study of Al deposition onto SiO 2 /Si substrates, in which the interaction between Al and SiO 2 has been well characterized. , First, using trial d diel , d metal values, the experimental (ψ, Δ) spectra were mathematically inverted to obtain a trial (ε 1 ,ε 2 ) metal . The constraint was applied that (ε 1 ,ε 2 ) metal must be free of Au interband transition artifacts in the 2.5 eV region.…”

Section: Resultsmentioning

confidence: 99%

Chemical Effects of Methyl and Methyl Ester Groups on the Nucleation and Growth of Vapor-Deposited Aluminum Films

et al. 1999

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The interaction of vapor-deposited Al atoms with self-assembled monolayers (SAMs) of HS(CH2)15CH3 and HS(CH2)15CO2CH3 chemisorbed at Au{111} surfaces was studied using X-ray photoelectron spectroscopy, infrared spectroscopy, time-of-flight secondary ion mass spectrometry, and spectroscopic ellipsometry. For the CH3-terminated SAM, no reaction with C−H or C−C bonds was observed. For total Al doses up to ∼12 atoms/nm2, penetration to the Au−S interface occurs with no disruption of the average chain conformation and tilt, indicating formation of a highly uniform ∼1:1 Al adlayer on the Au. Subsequently, penetration ceases and a metallic overlayer begins to form at the SAM−vacuum interface. These results are explained in terms of an initial dynamic hopping of the −S headgroups on the Au lattice, which opens transient diffusion channels to the Au−S interface, and the closing of these channels upon completion of the adlayer. In contrast, Al atom interactions with the CO2CH3-terminated SAM are restricted to the vacuum interface, where in the initial stages discrete organometallic products form via reaction with the CO2CH3 group. First, a 1:1 complex forms with a reduced CO bond and an intact CH3 moiety. Further exposure leads to the additional reaction of about four Al atoms per ester, after which a metallic overlayer nucleates in the form of clusters. After the growth progresses to ∼30 Å, the clusters coalesce into a uniform metallic film. These results illustrate the extraordinary degree of control that organic substrates can exert during the course of metal film formation.

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“…4). Used originally for exposing the undersides of MOS transistors by etching away the underlying substrate silicon (Hecht et al [62]), the applicability of XeF to micromachined sensors and actuators was demonstrated by Hoffman et al [63]. They showed that with a simple bell-jar setup run at 1 torr, XeF could be sublimed from its solid form at room temperature and that this etch has excellent selectivity with respect to CMOS process layers.…”

Section: Vapor-phase Etchingmentioning

confidence: 99%

Bulk micromachining of silicon

Kovacs

Maluf²,

Petersen³

1998

Proc. IEEE

659

374

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Bulk silicon etching techniques, used to selectively remove silicon from substrates, have been broadly applied in the fabrication of micromachined sensors, actuators, and structures. Despite the more recent emergence of higher resolution, surfacemicromachining approaches, the majority of currently shipping silicon sensors are made using bulk etching. Particularly in light of newly introduced dry etching methods compatible with complementary metal-oxide-semiconductors, it is unlikely that bulk micromachining will decrease in popularity in the near future. The available etching methods fall into three categories in terms of the state of the etchant: wet, vapor, and plasma. For each category, the available processes are reviewed and compared in terms of etch results, cost, complexity, process compatibility, and a number of other factors. In addition, several example micromachined structures are presented.

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A novel x-ray photoelectron spectroscopy study of the Al/SiO2 interface

Cited by 36 publications

References 26 publications

Thermal Atomic Layer Etching of SiO₂ by a “Conversion-Etch” Mechanism Using Sequential Reactions of Trimethylaluminum and Hydrogen Fluoride

Thermal Atomic Layer Etching of SiO₂ by a “Conversion-Etch” Mechanism Using Sequential Reactions of Trimethylaluminum and Hydrogen Fluoride

Chemical Effects of Methyl and Methyl Ester Groups on the Nucleation and Growth of Vapor-Deposited Aluminum Films

Bulk micromachining of silicon

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A novel x-ray photoelectron spectroscopy study of the Al/SiO2 interface

Cited by 36 publications

References 26 publications

Thermal Atomic Layer Etching of SiO2 by a “Conversion-Etch” Mechanism Using Sequential Reactions of Trimethylaluminum and Hydrogen Fluoride

Thermal Atomic Layer Etching of SiO2 by a “Conversion-Etch” Mechanism Using Sequential Reactions of Trimethylaluminum and Hydrogen Fluoride

Chemical Effects of Methyl and Methyl Ester Groups on the Nucleation and Growth of Vapor-Deposited Aluminum Films

Bulk micromachining of silicon

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Thermal Atomic Layer Etching of SiO₂ by a “Conversion-Etch” Mechanism Using Sequential Reactions of Trimethylaluminum and Hydrogen Fluoride

Thermal Atomic Layer Etching of SiO₂ by a “Conversion-Etch” Mechanism Using Sequential Reactions of Trimethylaluminum and Hydrogen Fluoride