Room Temperature Si–Si Direct Bonding Technique Using Velcro-Like Surfaces

Keshavarzi, Shervin; Mescheder, Ulrich; Reinecke, Holger

doi:10.1109/jmems.2016.2519823

Cited by 9 publications

(4 citation statements)

References 21 publications

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“…Various concepts of Velcro-like fasteners have been suggested so far [1][2][3]. The idea of employing NiTi shape memory alloys (SMA) for producing Velcro-like fasteners is not new.…”

Section: Introductionmentioning

confidence: 99%

Strength of Superelastic NiTi Velcro-Like Fasteners

Vokoun

Pilch

Kadeřávek

et al. 2021

Metals

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Velcro hook-and-loop fasteners invented more than 70 years ago are examples of the mechanism inspired by the tiny hooks found on the surface of burs of a plant commonly known as burdock. Several years ago, a novel Velcro-like fastener made of two arrays of hook-shaped thin NiTi wires was developed. Unique features of such fasteners, such as high thermally-tunable strength, fair force–stroke reproducibility, forceless contact or silent release, all derive from the superelasticity of the NiTi micro-wires. Recently, it was noticed that the presented fastener design allowed for a prediction of the number of active hooks. In this continuing study, the tension strength of the fastener was simulated as a function of hook density. Based on statistics, the model showed non-linear dependency of the number of interlocked hooks, N, on the hook density, m (N = round (0.21 m + 0.0035 m2 − 6.6)), for the simple hook pairs and the given hook geometry. The dependence of detachment force on stroke was simulated based on the Gaussian distribution of unhooking of individual hook connections along the stroke. The strength of the studied NiTi hook fasteners depended on hook density approximately linearly. The highest strength per cm2 reached at room temperature was 10.5 Ncm−2 for a density of m = 240 hooks/cm2.

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“…Various concepts of Velcro-like fasteners have been suggested so far [1][2][3]. The idea of employing NiTi shape memory alloys (SMA) for producing Velcro-like fasteners is not new.…”

Section: Introductionmentioning

confidence: 99%

Strength of Superelastic NiTi Velcro-Like Fasteners

Vokoun

Pilch

Kadeřávek

et al. 2021

Metals

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show abstract

“…2 Usage of the anodization technique to create needle-like Si surfaces for room temperature Si-Si bonding applications has currently attracted attention. [3][4][5] Additionally, the technique has a good potential to easily replace complicated and costly processes, such as inductively coupled plasma reactive ion etching (ICP-RIE), 6 interference lithography combined with Reactive Ion Etching (RIE) technique, 7 metal-assisted etching (MAE) technique, 8 and laser micro/nano-processing, 9 which are commonly used to generate Si needle-like antireflection coating surfaces for visible and (near infrared) NIR applications.…”

mentioning

confidence: 99%

“…Using the anodization technique, needle-like surfaces can be obtained by anodic etching of lowly doped p-type Si in aqueous HF solutions in the so-called transition region, the region between pore formation and electropolishing. [3][4][5] Although formation of PSi and electropolishing of p-type Si are quite well-understood, formation mechanisms of self-organized needles in the transition region, where both pore formation and electropolishing are competing for control over the surface, 10 is still unclear since instabilities in space and time are occurring in this region. 11 Even though formation mechanisms of needles generated by anodization of p-type Si are briefly described in, 12,13 no model for their formations has been reported yet.…”

mentioning

confidence: 99%

Formation Mechanisms of Self-Organized Needles in Porous Silicon Based Needle-Like Surfaces

Keshavarzi

Mescheder

Reinecke

2018

J. Electrochem. Soc.

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Formation mechanisms of self-organized Si-needles generated by anodic etching of lowly doped p-type silicon wafers in an aqueous HF solution in the transition region (region between the pore formation and the electropolishing) is studied through surface SEM images taken after different etch times. Impacts of current density, substrate resistivity range in the lowly doped region, and electrolyte additives on morphology of needles are also investigated. A simple model based on pore formation models is presented to describe formation of self-organized needles during anodic etching of lowly doped p-type silicon in an aqueous HF solution in the transition region. Anodization is a well-known technique for porous silicon (PSi) formation or electropolishing of silicon (Si) wafers. Although the technique is known for several decades, it has attracted renewed interest since 1990 resulting from discovery of luminescence properties of PSi.1 The technique has also emerged in micromachining due to its low cost, easy implementation, and compatibility with standard microelectronic processes.2 Usage of the anodization technique to create needle-like Si surfaces for room temperature Si-Si bonding applications has currently attracted attention.3-5 Additionally, the technique has a good potential to easily replace complicated and costly processes, such as inductively coupled plasma reactive ion etching (ICP-RIE), 6 interference lithography combined with Reactive Ion Etching (RIE) technique, 7 metal-assisted etching (MAE) technique, 8 and laser micro/nano-processing, 9 which are commonly used to generate Si needle-like antireflection coating surfaces for visible and (near infrared) NIR applications.Using the anodization technique, needle-like surfaces can be obtained by anodic etching of lowly doped p-type Si in aqueous HF solutions in the so-called transition region, the region between pore formation and electropolishing.3-5 Although formation of PSi and electropolishing of p-type Si are quite well-understood, formation mechanisms of self-organized needles in the transition region, where both pore formation and electropolishing are competing for control over the surface, 10 is still unclear since instabilities in space and time are occurring in this region.11 Even though formation mechanisms of needles generated by anodization of p-type Si are briefly described in, 12,13 no model for their formations has been reported yet. In this work, formation mechanisms of self-organized needles generated by anodic etching of lowly doped (<10 15 atoms/cm 3 ) 14 p-type Si in an aqueous HF solution is investigated in detail. Impacts of current density and substrate resistivity range in the lowly doped region, and electrolyte additives on morphology of surfaces are also discussed. A simple model based on the Current Burst (CB) model, 15 the Zhang model (distribution of the electric field at different regions of a pore), 16 and the Lehmann macro-pore formation model 17 is then presented to describe formation of needles in the transition region. Exp...

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“…However, direct bonding technology is being studied and applied for some device fabrication to replace soldering bonding technology to achieve higher performance packaging. [1][2][3] For Cu/Cu direct bonding, usually, high temperature should be required to achieve good mechanical performance for direct bonding. However, high temperature may cause some problems for some devices, such as performance degeneration and device damage.…”

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confidence: 99%

Study of Cu Film Surface Treatment Using Formic Acid Vapor/Solution for Low Temperature Bonding

Yang

Zhou

et al. 2017

J. Electrochem. Soc.

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In this paper, the surface of Cu film was treated with formic acid vapor and solution for Cu low temperature bonding. After formic acid vapor/solution treatment, Cu film surface oxide was reduced, and surface became rougher. For formic acid vapor treatment, with the increase of treatment time, Cu film surface was reduced gradually at 200 • C, surface roughness and particle size became bigger. For formic acid solution treatment, the reduction of the surface of the copper film was the most abundant when the solution concentration is 50%. After the treatment with formic acid solution, the surface roughness and particle size of copper film increase significantly. As the formic acid solution on the surface of copper film has a certain role in corrosion, using formic acid solution treatment, better surface reduction and rougher surface for Cu film were obtained. By contrast, using formic acid vapor treatment, surface reduction is not so good, but surface is smoother than that treated by formic acid solution. Cu/Cu direct bonding was realized at 200 • C after formic acid vapor/solution treatment. Using formic acid vapor treatment, Cu/Cu bond strength is about 18.2 MPa, which is higher than that using formic acid solution treatment.

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Room Temperature Si–Si Direct Bonding Technique Using Velcro-Like Surfaces

Cited by 9 publications

References 21 publications

Strength of Superelastic NiTi Velcro-Like Fasteners

Strength of Superelastic NiTi Velcro-Like Fasteners

Formation Mechanisms of Self-Organized Needles in Porous Silicon Based Needle-Like Surfaces

Study of Cu Film Surface Treatment Using Formic Acid Vapor/Solution for Low Temperature Bonding

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