One-step maskless grayscale lithography for the fabrication of 3-dimensional structures in SU-8

Rammohan, A.; Dwivedi, Prabhat K.; Martínez-Duarte, Rodrigo; Katepalli, Hari; Madou, Marc; Sharma, Ashutosh

doi:10.1016/j.snb.2010.10.021

Cited by 115 publications

(85 citation statements)

References 22 publications

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“…Examples of SU-8 grayscale features obtained with this type of maskless lithography are shown in Figure 2. The characterization of the exposure dose depending on the grayscale used in software, as well as other processing parameters, have been detailed elsewhere by this author and his collaborators [42]. …”

Section: Grayscale Photolithographymentioning

confidence: 99%

SU-8 Photolithography as a Toolbox for Carbon MEMS

Martínez-Duarte

2014

Micromachines

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Abstract:The use of SU-8 as precursor for glass-like carbon, or glassy carbon, is presented here. SU-8 carbonizes when subject to high temperature under inert atmosphere. Although epoxy-based precursors can be patterned in a variety of ways, photolithography is chosen due to its resolution and reproducibility. Here, a number of improvements to traditional photolithography are introduced to increase the versatility of the process. The shrinkage of SU-8 during carbonization is then detailed as one of the guidelines necessary to design carbon patterns. A couple of applications-(1) carbon-electrode dielectrophoresis for bioparticle manipulation; and (2) the use of carbon structures as micro-molds are also presented.

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Section: Grayscale Photolithographymentioning

confidence: 99%

SU-8 Photolithography as a Toolbox for Carbon MEMS

Martínez-Duarte

2014

Micromachines

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“…The patterning of the SU-8 by lithography allows microstructures of almost any shape and size; not only planar microstructures, but also multilayer and 3D microstructures [8]. For that, several lithographic techniques can be used, such as, layer-by-layer multi exposure lithography [8,9], inclined/rotated lithography [8,10], holographic lithography, and gray-scale lithography [8,11]. Figure 1 shows the SU-8 processing steps and the respective equipment used that allows the fabrication of microstructures with aspect ratios of more than 20, with low-cost and without cleanroom facility.…”

Section: Su-8 Processing Using Low-cost Facilitiesmentioning

confidence: 99%

“…The gray-scale lithography is typically implemented using gray shades mask allowing the modulation of the exposure dose that reaches the photoresist. With this modulation, different penetration depths of the radiation are obtained resulting in a 3D structure after development [8,11]. This type of photolithography uses similar steps of the traditional photolithography differing only in the mask used in the UV exposure step.…”

Section: Gray-scale Lithographymentioning

confidence: 99%

“…This type of photolithography uses similar steps of the traditional photolithography differing only in the mask used in the UV exposure step. They are gray-scale masks that are fabricated using the dots per inch (dpi) variation across the mask [11]. The gray levels are obtained from pseudo gray-scale, which are generated by dots with different sizes and densities.…”

Section: Gray-scale Lithographymentioning

confidence: 99%

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Optimized SU-8 Processing for Low-Cost Microstructures Fabrication without Cleanroom Facilities

et al. 2014

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Abstract:The study and optimization of epoxy-based negative photoresist (SU-8) microstructures through a low-cost process and without the need for cleanroom facility is presented in this paper. It is demonstrated that the Ultraviolet Rays (UV) exposure equipment, commonly used in the Printed Circuit Board (PCB) industry, can replace the more expensive and less available equipment, as the Mask Aligner that has been used in the last 15 years for SU-8 patterning. Moreover, high transparency masks, printed in a photomask, are used, instead of expensive chromium masks. The fabrication of well-defined SU-8 microstructures with aspect ratios more than 20 is successfully demonstrated with those facilities. The viability of using the gray-scale technology in the photomasks for the fabrication of 3D microstructures is also reported. Moreover, SU-8 microstructures for different applications are shown throughout the paper.

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“…UV dosage control is also possible in grayscale lithography [48]. Rammohan et al utilized the use of grayscale maskless lithography in a single-layer of SU-8 to demonstrate 3D microstructures such as air-suspended cantilevers, microneedles and embedded microfluidic channels [49]. In the case of microfluidic channels, micro ridges and micro pillars with different exposure doses than the sidewall were utilized to form passive mixing microfluidic channels.…”

Section: Moving-mask Lithography and Maskless Grayscale Lithographymentioning

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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One-step maskless grayscale lithography for the fabrication of 3-dimensional structures in SU-8

Cited by 115 publications

References 22 publications

SU-8 Photolithography as a Toolbox for Carbon MEMS

SU-8 Photolithography as a Toolbox for Carbon MEMS

Optimized SU-8 Processing for Low-Cost Microstructures Fabrication without Cleanroom Facilities

Innovative SU-8 Lithography Techniques and Their Applications

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