Microfabrication of 3D multidirectional inclined structures by UV lithography and electroplating

Beuret, C.; Racine, G.-A.; Gobet, J.; Luthier, R.; Rooij, N. F. de

doi:10.1109/memsys.1994.555602

Cited by 63 publications

(36 citation statements)

References 7 publications

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“…Previous technologies used multiple direct writing and photolithography steps, or customized equipment [21][22][23][24][25]. However, these technologies are restricted to a limited range of shapes and do not utilize batch processing.…”

Section: Engineered Contacts Using Gray-scale Lithographymentioning

confidence: 99%

Micro-Contacts Testing using a Micro-Force Sensor Compatible with Biological Systems

Coutu¹,

Tomer²

2017

IJBSBE

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This paper presents the performance and reliability testing of microelectromechanical systems (MEMS) switches by using a micro-force sensor which was originally designed/used to conduct mechanical testing of biological cells. MEMS switches are key components for radio frequency (RF) applications due to their extremely low power consumption and small geometries over conventional technologies. However, unstable electrical contact resistance severely degrades the performance and reliability of such micro-switches. Therefore, our focus is to improve the performance and reliability of "cold" switched micro-contacts by using novel contact materials and engineered micro-contact surfaces. The contact metallurgies considered in this work are "similar" thin film combinations of Au, and composite Au/CNT. The nonengineered switch consists of a metallic hemispherical bump and a planar sheet as upper and lower contacts, respectively. On the other hand, the engineered switches have 2D pyramid structure in lower contacts while having a hemispherical bump at upper contact. Hemisphere on planar, Au-Au, contact pairs resulted in initial contact resistance (R C ) values of ~0.1Ω (F C = 200µN) that linearly increased to ~1.0Ω after ~10×10 6 cycles and then failed open (~10.0Ω) at ~20×10 6 switching cycles. The AuAu/CNT composite, hemisphere on planar contact pair showed similar R C performance with extended reliability (~40×10 6 switching cycles) when the composite film was integrated into the lower planar contacted. Upper hemisphere on the 2D pyramid, Au-Au, contact pairs resulted in initial R C values of ~0.9Ω (F C = 200µN) that linearly decreased to ~0.5Ω at >10×10 6 cycles (not failed). This work suggests that the combination of engineered lower contacts and composite materials can significantly improve the performance and reliability of micro-switches.

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Section: Engineered Contacts Using Gray-scale Lithographymentioning

confidence: 99%

Micro-Contacts Testing using a Micro-Force Sensor Compatible with Biological Systems

Coutu¹,

Tomer²

2017

IJBSBE

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“…The first pioneering unconventional UV lithography might be demonstration of thick 3D multi-directional inclined microstructures by Beuret et al [13]. This work used two layers of positive photoresists (AZ 4562) and two slighltly shifted metallic layers directly on the photoresist layers as integrated masks.…”

Section: Inclined Uv Exposurementioning

confidence: 99%

Innovative SU-8 Lithography Techniques and Their Applications

2014

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SU-8 has been widely used in a variety of applications for creating structures in micro-scale as well as sub-micron scales for more than 15 years. One of the most common structures made of SU-8 is tall (up to millimeters) high-aspect-ratio (up to 100:1) 3D microstructure, which is far better than that made of any other photoresists. There has been a great deal of efforts in developing innovative unconventional lithography techniques to fully utilize the thick high aspect ratio nature of the SU-8 photoresist. Those unconventional lithography techniques include inclined ultraviolet (UV) exposure, back-side UV exposure, drawing lithography, and moving-mask UV lithography. In addition, since SU-8 is a negative-tone photoresist, it has been a popular choice of material for multiple-photon interference lithography for the periodic structure in scales down to deep sub-microns such as photonic crystals. These innovative lithography techniques for SU-8 have led to a lot of unprecedented capabilities for creating unique micro-and nano-structures. This paper reviews such innovative lithography techniques developed in the past 15 years or so.

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“…3D metal structures have been achieved with angled sidewalls by using a rotating light source in a customized lithography setup and then electroplating [24]. A rotating light source exposes the desired film at an angle (through two separate masks) and upon development and electroplating, an angled structure may be created.…”

Section: Dimensional Mems Fabricationmentioning

confidence: 99%

Development of a Deep Silicon Phase Fresnel Lens Using Gray-Scale Lithography and Deep Reactive Ion Etching

Morgan

Waits

Krizmanic

et al. 2004

J. Microelectromech. Syst.

125

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A phase Fresnel lens (PFL) could achieve higher sensitivity and angular resolution in astronomical observations than the current generation of gamma and hard x-ray instruments. For ground tests of a PFL system, silicon lenses must be fabricated on the micro-scale with controlled profiles to enable high lens efficiency. Thus, two MEMS-based technologies, gray-scale lithography and deep reactive ion etching (DRIE), are extended to create multiple controlled step heights in silicon on the necessary scale.A Gaussian approximation is introduced as a method of predicting a photoresist gray level height given the amount of transmitted light through a grayscale optical mask. Etch selectivity during DRIE is then accurately controlled by introducing an oxygen-only step to a standard Bosch cycle to produce the desired scaling factor between the photoresist and silicon profiles. Finally, a profile evaluation method is developed to calculate the expected efficiency of measured silicon profiles. Calculated efficiencies above 87% have been achieved.

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Microfabrication of 3D multidirectional inclined structures by UV lithography and electroplating

Cited by 63 publications

References 7 publications

Micro-Contacts Testing using a Micro-Force Sensor Compatible with Biological Systems

Micro-Contacts Testing using a Micro-Force Sensor Compatible with Biological Systems

Innovative SU-8 Lithography Techniques and Their Applications

Development of a Deep Silicon Phase Fresnel Lens Using Gray-Scale Lithography and Deep Reactive Ion Etching

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