SU-8 nanocomposite coatings with improved tribological performance for MEMS

Jiguet, Sébastien; Judelewicz, Moshe; Mischler, S.; Hofmann, Heinrich; Bertsch, Arnaud; Renaud, Philippe

doi:10.1016/j.surfcoat.2006.03.041

Cited by 43 publications

(26 citation statements)

References 11 publications

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“…Other advantages include, relatively low price, the feasibility of batch processing, high thermal stability, good chemical resistance and low optical absorption. SU8 properties are not solely dependent on crosslink density which in turns depends on curing conditions, but also lately there are studies involving SU8 nanocomposites aiming to enhance its performance using nanomaterials [10,[12][13][14][15]. Shortcomings of these composites are complication in fabrication as well as high cost.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Conventional and Variable Frequency Microwave Curing of SU8 Photoresist: Effects on the Dielectric, Thermal, and Morphological Properties

Wattanachai

Antonio

2016

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Abstract. Variable Frequency Microwave (VFM) is known to be a rapid, volumetric, and selective form of heating which has shown potential as an alternative technique for the processing of negative-tone SU8 photoresist in the Micro-Electro-Mechanical System (MEMS) industry. A comparison of thermal properties of the films cured during the softbake and post exposure bake process using different techniques, i.e. conventional thermal curing, VFM curing, and a combination of both (referred to as hybrid, HY), was investigated using a Differential Scanning Calorimeter (DSC) and Thermogravimetric Analysis (TGA). A significant increase on the degree of cure (between 13-23%) was observed using the VFM over the hybrid and hotplate curing which means that SU8 curing at lower temperatures or rapid curing is possible. The increase in cure rates can be attributed to a combination of heat transfer and the unique capability of microwave to couple with the sample (selective heating). The improvement in curing at the same processing temperatures has important implications for processing thick films. It was found that regardless of curing methods, crosslink densities increased as the baking temperature increased, resulting in lower dielectric properties. Despite higher crosslinking contents, VFM cured samples decomposed at 2-4°C lower temperatures. In addition to better thermal properties, VFM offered satisfactory microstructure at lower curing temperatures; however, high processing temperatures could result in film cracking.

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Section: Introductionmentioning

confidence: 99%

Comparison of Conventional and Variable Frequency Microwave Curing of SU8 Photoresist: Effects on the Dielectric, Thermal, and Morphological Properties

Wattanachai

Antonio

2016

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“…Mixing of SU-8 with other compounds before processing is in general a very convenient way of tuning bulk and/or surface properties. Several properties of SU-8 such as electrical [12], piezoelectric [13] and tribological [14] have been manipulated by compositing SU-8 with additives. However, to our knowledge, no investigations have so far been conducted on improving tribological properties of SU-8 through compositing with lubricating materials.…”

Section: Introductionmentioning

confidence: 99%

Novel SU-8/Ionic Liquid Composite for Tribological Coatings and MEMS

Batooli

Maldonado

Judelewicz³

et al. 2015

Micromachines

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Tribology of SU-8 polymer is increasingly relevant due to bursting use of this material in a variety of applications. This study is directed towards introduction and investigation of a novel self-lubricating composite of an ionic liquid (IL) in SU-8. The new material can be utilized for fabrication of lubricating polymer coating with tunable surface properties or SU8-made elements for microelectromechanical systems (MEMS) with enhanced tribological performance. It is shown that addition of IL drastically alters water affinity of the composite while UV patternability remains unmodified. A lower coefficient of friction and wear has been obtained for two investigated compositions with 4 and 10 wt % ionic liquid.

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“…For example sensors [3] and microlenses [4] have been fabricated out of SU8 as have templates for soft lithographic techniques [5,6] and functional surfaces displaying properties such as superhydrophobicity [2]. The inclusion of particles in SU8 can be done to impart greater functionality on the final structure, an example of this being the inclusion of SiO 2 particles in an SU8 matrix to increase wear resistance [7]. Carbon nanotubes have also been used as inclusions within a SU8 matrix to make an inkjet-printable conductive composite [8] and SU8 / ZnO nanoparticle composites have been investigated as piezoelectric materials [9].…”

Section: Introductionmentioning

confidence: 99%

Lithographically fabricated SU8 composite structures for wettability control

Hamlett

McHale

Newton

2014

Surface and Coatings Technology

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SU8 is a negative resist which is widely used for the fabrication of micron scale lateral features over a wide range of heights using photolithographic methods. This has been extensively used as a method to produce surface structure to which hydrophobicity can be added and a model super-water repellent surface of achieved. However, such an approach requires at least two-steps and does not embed the desired properties as part of the structure itself or create multiple levels of topographical structure. In other applications, a variety of inclusions have previously been studied to tailor the properties of SU8. In this work we report an approach to, and results from, incorporating inclusions, in our case glass beads, of different wettabilities into the SU8 structures produced by photolithography. In particular, we focus on ridge structures expected to be of use in flow systems as drag reducing surfaces. We used scanning electron microscopy and profilometry to investigate how the inclusion of either hydrophobic or hydrophilic glass beads (sieve size of 20-30 μm) affects the definition of the structures formed and contact angle goniometry to define what effect such inclusions has on the wettability of the SU8 composite structure. It was found that the inclusion of hydrophobic glass beads in the SU8 resist resulted in poorly defined structures compared to both SU8 on its own and SU8 to which hydrophobic glass beads were added. In contrast, inclusion of hydrophilic glass beads resulted in a well-defined ridge structure with the majority of the beads located in the 'valleys'. Both EDX analysis and contact angle data indicated that the surface chemistry of the beads themselves (both the hydrophobic and hydrophilic beads) were masked by the SU8. Counter-intuitively, the inclusion of hydrophobic beads in the SU8 composite resin resulted in ridges with increased wettability, compared to SU8 ridges, as opposed to the inclusions of hydrophilic beads that resulted in surfaces with increased effective hydrophobicity .2

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SU-8 nanocomposite coatings with improved tribological performance for MEMS

Cited by 43 publications

References 11 publications

Comparison of Conventional and Variable Frequency Microwave Curing of SU8 Photoresist: Effects on the Dielectric, Thermal, and Morphological Properties

Comparison of Conventional and Variable Frequency Microwave Curing of SU8 Photoresist: Effects on the Dielectric, Thermal, and Morphological Properties

Novel SU-8/Ionic Liquid Composite for Tribological Coatings and MEMS

Lithographically fabricated SU8 composite structures for wettability control

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