Implementing ALD Layers in MEMS Processing

Puurunen, Riikka L.; Saarilahti, Jaakko; Kattelus, Hannu

doi:10.1149/1.2779063

Cited by 70 publications

(45 citation statements)

References 10 publications

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“…18 This renders ALD its precise thickness control and good conformality 19 and uniformity of the produced film, which make ALD a viable method, for example, for complex NEMS fabrication. 20 However, the thermal ALD of nitrides suffers from poor reactivity of the conventional nitrogen precursors [e.g., ammonia (NH 3 )] at typical ALD temperatures (≤500°C) which has a negative effect on the film quality. 8,21 In order to overcome the issue of the low reactivity in thermal ALD, PEALD is commonly applied in which the nitrogen precursor is plasma activated.…”

Section: Introductionmentioning

confidence: 99%

Comparison of mechanical properties and composition of magnetron sputter and plasma enhanced atomic layer deposition aluminum nitride films

Sippola

Perros

Ylivaara

et al. 2018

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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A comparative study of mechanical properties and elemental and structural composition was made for aluminum nitride thin films deposited with reactive magnetron sputtering and plasma enhanced atomic layer deposition (PEALD). The sputtered films were deposited on Si (100), Mo (110), and Al (111) oriented substrates to study the effect of substrate texture on film properties. For the PEALD trimethylaluminum-ammonia films, the effects of process parameters, such as temperature, bias voltage, and plasma gas (ammonia versus N 2 /H 2 ), on the AlN properties were studied. All the AlN films had a nominal thickness of 100 nm. Time-of-flight elastic recoil detection analysis showed the sputtered films to have lower impurity concentration with an Al/N ratio of 0.95, while the Al/N ratio for the PEALD films was 0.81-0.90. The mass densities were ∼3.10 and ∼2.70 g/cm 3 for sputtered and PEALD AlN, respectively. The sputtered films were found to have higher degrees of preferential crystallinity, whereas the PEALD films were more polycrystalline as determined by x-ray diffraction. Nanoindentation experiments showed the elastic modulus and hardness to be 250 and 22 GPa, respectively, for sputtered AlN on the (110) substrate, whereas with PEALD AlN, values of 180 and 19 GPa, respectively, were obtained. The sputtered films were under tensile residual stress (61-421 MPa), whereas the PEALD films had a residual stress ranging from tensile to compressive (846 to −47 MPa), and high plasma bias resulted in compressive films. The adhesion of both films was good on Si, although sputtered films showed more inconsistent critical load behavior. Also, the substrate underneath the sputtered AlN did not withstand high wear forces as with the PEALD AlN. The coefficient of friction was determined to be ∼0.2 for both AlN types, and their wear characteristics were almost identical. Published by the AVS.

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Section: Introductionmentioning

confidence: 99%

Comparison of mechanical properties and composition of magnetron sputter and plasma enhanced atomic layer deposition aluminum nitride films

Sippola

Perros

Ylivaara

et al. 2018

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

Self Cite

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“…Furthermore, the redeposition of Al on Si has been shown to be directly proportional to the amount of contaminant Al in SC-1. 13 ALD alumina has already displayed potential as a thin-film material with a low etch rate in a variety of solutions including SC-2; 14 however, in general, the as-deposited ALD Al 2 O 3 films tend to be amorphous 15 and unstable in many solutions. For example, as-deposited ALD Al 2 O 3 has been reported to be susceptible to water corrosion.…”

Section: Introductionmentioning

confidence: 99%

“…1, 14 The elevated temperature treatments cause the amorphous microstructure of ALD alumina to densify and to change its composition. 16 Thermal treatments at elevated temperatures lead to phase transformations of alumina and to a reduced degree of hydration.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of the Humidity Calibration Chamber by Numerical Simulations

et al. 2017

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Atomic-layer-deposited alumina (ALD Al 2 O 3 ) can be utilized for passivation, structural, and functional purposes in electronics. In all cases, the deposited film is usually expected to maintain chemical stability over the lifetime of the device or during processing. However, as-deposited ALD Al 2 O 3 is typically amorphous with poor resistance to chemical attack by aggressive solutions employed in electronics manufacturing. Therefore, such films may not be suitable for further processing as solvent treatments could weaken the protective barrier properties of the film or dissolved material could contaminate the solvent baths, which can cause crosscontamination of a production line used to manufacture different products. On the contrary, heat-treated, crystalline ALD Al 2 O 3 has shown resistance to deterioration in solutions, such as standard clean (SC) 1 and 2. In this study, ALD Al 2 O 3 was deposited from four different precursor combinations and subsequently annealed either at 600, 800, or 1000°C for 1 h. Crystalline Al 2 O 3 was achieved after the 800 and 1000°C heat treatments. The crystalline films showed apparent stability in SC-1 and HF solutions. However, ellipsometry and electron microscopy showed that a prolonged exposure (60 min) to SC-1 and HF had induced a decrease in the refractive index and nanocracks in the films annealed at 800°C. The degradation mechanism of the unstable crystalline film and the microstructure of the film, fully stable in SC-1 and with minor reaction with HF, were studied with transmission electron microscopy. Although both crystallized films had the same alumina transition phase, the film annealed at 800°C in N 2 , with a less developed microstructure such as embedded amorphous regions and an uneven interfacial reaction layer, deteriorates at the amorphous regions and at the substrate−film interface. On the contrary, the stable film annealed at 1000°C in N 2 had considerably less embedded amorphous regions and a uniform Al−O−Si interfacial layer.

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“…Therefore, we can conclude that the as‐deposited 5 nm film is amorphous. For further confirmation, a wet etching procedure as described in the supporting information was employed to distinguish between crystalline and amorphous layers . Only the thinnest 5 nm TiO 2 layers were removed using a wet etching step while the thicker 10 nm layers remain unaffected (see Table S1, Supporting Information) confirming their crystallinity.…”

Section: Resultsmentioning

confidence: 99%

Photocatalytic Lithography with Atomic Layer–Deposited TiO₂ Films to Tailor Biointerface Properties

Vandenbroucke

Mattelaer

Jans

et al. 2019

Adv Materials Inter

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In this article, the use of thin, photocatalytically active TiO2 films deposited using atomic layer deposition (ALD) and a conventional lithography mask are explored for the fabrication of a patterned biointerface. Hereto, a pattern of self‐assembled monolayers (SAMs) with different functional groups is created using ALD TiO2 films, anatase‐rich as‐deposited, with a thickness of 20 nm and a short UV exposure time of 5 min. More specifically, azido‐containing SAMs are locally removed upon UV exposure (λ = 308 nm) and the created gaps are filled with a polyethylene glycol (PEG) SAM, hereby creating a surface with areas for the selective coupling of biomolecules via the azide groups and antifouling areas due to the presence of the PEG. To demonstrate the effectiveness of this approach, fluorescent‐labeled antibodies are immobilized on the well‐defined patterns with a resolution in the µm range.

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Implementing ALD Layers in MEMS Processing

Cited by 70 publications

References 10 publications

Comparison of mechanical properties and composition of magnetron sputter and plasma enhanced atomic layer deposition aluminum nitride films

Comparison of mechanical properties and composition of magnetron sputter and plasma enhanced atomic layer deposition aluminum nitride films

Characterization of the Humidity Calibration Chamber by Numerical Simulations

Photocatalytic Lithography with Atomic Layer–Deposited TiO₂ Films to Tailor Biointerface Properties

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Implementing ALD Layers in MEMS Processing

Cited by 70 publications

References 10 publications

Comparison of mechanical properties and composition of magnetron sputter and plasma enhanced atomic layer deposition aluminum nitride films

Comparison of mechanical properties and composition of magnetron sputter and plasma enhanced atomic layer deposition aluminum nitride films

Characterization of the Humidity Calibration Chamber by Numerical Simulations

Photocatalytic Lithography with Atomic Layer–Deposited TiO2 Films to Tailor Biointerface Properties

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Product

Resources

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Photocatalytic Lithography with Atomic Layer–Deposited TiO₂ Films to Tailor Biointerface Properties