Extension of the Stoney formula for the incremental stress of thin films

Qiang, Jun; Jiang, Bingyan; Dong, Yanzhuo; Roth, Benedikt; Jiang, Fengze

doi:10.1063/5.0038257

Cited by 11 publications

(2 citation statements)

References 26 publications

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“…tensile) induces a positive increase of the wafer curvature. Note that the first order terms involving the thickness ratio are ignored [48,49] in equation ( 1) owing to its small value for the present structures (<0.003) and due to the bulk modulus of the epilayer and the substrate material being of the same order. For a multilayer film, equation ( 2) can be further extended when the total curvature is a non-weighted superposition of the contributions from each layer i.e.…”

Section: Theoretical Frameworkmentioning

confidence: 99%

Design of step-graded AlGaN buffers for GaN-on-Si heterostructures grown by MOCVD

Ghosh

Hinz

Frentrup

et al. 2023

Semicond. Sci. Technol.

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For the growth of low-defect crack-free GaN heterostructures on large-area silicon substrates, compositional grading of AlGaN is a widely adapted buffer technique to restrict the propagation of lattice-mismatch induced defects and balance the thermal expansion mismatch-induced tensile stress. So far, a consolidation of the design strategy of such step-graded buffers has been impaired by the incomplete understanding of the effect of individual buffer design parameters on the mechanical and microstructural properties of the epilayers. Herein, we have analysed a series of metal-organic chemical vapor deposition (MOCVD) grown GaN/graded-AlGaN/AlN/Si heterostructures through in situ curvature measurements and post-growth X-ray diffraction (XRD). Our results reveal that in such epi structures, the GaN layer itself induces more compressive stress than the AlGaN buffer, but the underlying AlGaN layers dictate the magnitude of this stress. Furthermore, for a fixed AlGaN buffer thickness, the mean-stress accumulated during the GaN growth is found to be correlated with its structural properties. Specifically, one µm-thick GaN layers that acquire 1.50 GPa or higher compressive mean-stress are seen to possess XRD ω-FWHM values less than 650 arc-sec. Also, the evolution of instantaneous stresses during the growth of the AlGaN layers is found to be a valuable indicator for buffer optimization, and composition difference between successive layers is established as a crucial criterion. The results also show that increasing the total buffer thickness (for a fixed number of steps) or increasing the number of steps (for a fixed total buffer thickness) may not always be beneficial. Irrespective of the buffer thickness, optimized high electron mobility transistor (HEMT) structures show similarly low sheet-resistance (~ 350 Ω/□) and high mobility (~ 2000 cm2/V-s) at room temperature.

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Section: Theoretical Frameworkmentioning

confidence: 99%

Design of step-graded AlGaN buffers for GaN-on-Si heterostructures grown by MOCVD

Ghosh

Hinz

Frentrup

et al. 2023

Semicond. Sci. Technol.

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“…Silicon master was prepared by UV lithography (URE-2000135, Chengdu, China) and followed by the reactive ion etching (ULVAC NLD 570, Kanagawa, Japan). A self-designed electroforming device (V-30L, Changsha, China), as shown in Figure 3, was used to fabricate the Ni mold insert [29]. Sputtering coater (Leica EMSCD500, Wetzlar, Germany) was used to conduct the silicon master by depositing a gold layer on the surface, so that the metal ions will be effectively transferred and deposited on the silicon master in the later electroforming process.…”

Section: Fabrication Of Mold Insertmentioning

confidence: 99%

Self-Assembled Monolayers of Alkanethiols on Nickel Insert: Characterization of Friction and Analysis on Demolding Quality in Microinjection Molding

et al. 2021

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When the part geometry scaling down from macro to microscale level, the size-induced surface effect becomes significant in the injection molding process. The adhesion between polymer and nickel (Ni) mold insert during the process can lead to defects in necking, warping and deformation of microstructure. In this study, the self-assembled monolayers (SAMs) with low surface energy were deposited on the Ni surface to reduce the adhesion and further improve the demolding quality of the microstructure. Results show that the alkyl mercaptan SAMs with chemical bonds and close alignment can be successfully deposited on the surface of Ni by the solution deposition method. The contact angle, surface free energy, and friction coefficient before and after anti-adhesion treatment on the surface of mold insert were measured. In addition, the anti-adhesion properties of different alkyl mercaptan materials and the correspondingly replication quality of microstructure parts after injection molding were analyzed. It is found that the Ni mold insert treated by the perfluorodecanethiol has the best wear resistance and still shows good reproducibility at the 100th demolding cycle.

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Thickness-dependent structure and properties in zirconium carbide ceramic via orientated deposition

Quan,

Gao,

Guo

et al. 2024

Applied Surface Science

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Extension of the Stoney formula for the incremental stress of thin films

Cited by 11 publications

References 26 publications

Design of step-graded AlGaN buffers for GaN-on-Si heterostructures grown by MOCVD

Design of step-graded AlGaN buffers for GaN-on-Si heterostructures grown by MOCVD

Self-Assembled Monolayers of Alkanethiols on Nickel Insert: Characterization of Friction and Analysis on Demolding Quality in Microinjection Molding

Thickness-dependent structure and properties in zirconium carbide ceramic via orientated deposition

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