One-step 3D shaping using a gray-tone mask for optical and microelectronic applications

Oppliger, Y.; Sixt, Pierre; Stauffer, J. M.; Mayor, J. M.; Regnault, P.; Voirin, Guy

doi:10.1016/0167-9317(94)90193-7

Cited by 108 publications

(44 citation statements)

References 1 publication

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“…Therefore, the UV transmission pattern controls the dose delivered to the photoresist. The mechanism to control the UV intensity gradient in gray-scale photolithography varies with each technique and has been demonstrated with pixelated [27][28][29][30][31][32][33] and continuous-tone [34,35] optical masks. Pixelated gray-scale masks use diffraction through many sub-resolution pixels to control the UV dose.…”

Section: Gray-scale Masksmentioning

confidence: 99%

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Double-Exposure Grayscale Photolithography

Mosher

Waits

Morgan

et al. 2009

J. Microelectromech. Syst.

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Three-dimensional (3D) photoresist structures may be realized by controlling the transmitted UV light intensity in a process termed gray-scale photolithography.Light modulation is accomplished by diffraction through sub-resolution pixels on a photomask. The number of photoresist levels is determined by the number of different pixel sizes on the mask, which is restricted by mask fabrication. This drawback prevents the use of gray-scale photolithography for applications that need a high vertical resolution.The double-exposure gray-scale photolithography technique was developed to improve the vertical resolution without increasing the number of pixel sizes. This is achieved by using two gray-scale exposures prior to development. The resulting overlay produces an exposure dose that is a combination of both exposures.Calibration is utilized to relate the pixel sizes and exposure times to the photoresist height. This calibration enables automated mask design for arbitrary 3D structures and investigation of other effects, such as misalignment between the exposures.

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Section: Gray-scale Masksmentioning

confidence: 99%

“…Three-dimensional photolithography using a gray-scale mask [27][28][29][30][31][32][33][34][35][36] is capable of realizing structures with a higher vertical resolution than multipleexposure photolithography while still using conventional photolithography tools.…”

Section: Gray-scale Masksmentioning

confidence: 99%

Double-Exposure Grayscale Photolithography

Mosher

Waits

Morgan

et al. 2009

J. Microelectromech. Syst.

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“…The gray-scale photomask technique [6] is used in our fabrication process to make sloped sacrificial photoresist. Such a typical mask is shown in Fig.2.…”

Section: Sloped Photoresistmentioning

confidence: 99%

Cracking pressure control of parylene checkvalve using slanted tensile tethers

Lin

Tai

2010

2010 IEEE 23rd International Conference on Micro Electro Mechanical Systems (MEMS)

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MEMS check valves with fixed cracking pressures are important in micro-fluidic applications where the pressure, flow directions and flow rates all need to be carefully controlled. This work presents a new surface-micromachined parylene check valve that uses residual thermal stress in the parylene to control its cracking pressure. The new check valve uses slanted tethers to allow the parylene tensile stress to apply a net downward force on the valving seat against the orifice. The angle of the slanted tethers is made using a gray-scale mask to create a sloped sacrificial photoresist with the following tether parylene deposition. The resulted check valves have both the cracking pressures and flow profiles agreeable well with our theoretical analysis.

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“…Usually, 3D photoresist microstructure is realized by using a gray tone UV exposure technique to control the development rate, and therefore the final development depth in photoresist. Several approaches for grayscale lithography has been proposed such as grayscale mask lithography [3], moving-mask UV lithography [4], and digital micromirror device (DMD)-based grayscale lithography [5]- [7]. Among many grayscale lithography approaches, DMD-based grayscale lithography has recently been receiving much attention because DMD can project the grayscale mask pattern according to the pixel information of a bitmap instead of relying on a highresolution optical photomask (i.e., maskless approach as shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Optimization methods for 3D lithography process utilizing DMD-based maskless grayscale photolithography system

Kato

Hirai

et al. 2015

SPIE Proceedings

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Digital Micromirror Device (DMD)-based grayscale lithography is a promising tool for three dimensional (3D) microstructuring of thick-film photoresist since it is a maskless process, provides possibility for the free-form of 3D microstructures, and therefore rapid and cost-effective microfabrication. However, process parameter determination lacks efficient optimization tool, and thus conventional look-up table (indicating the relationship between development depth and exposure dose value under a fixed development time) approach with manual try-and-error adjustment is still gold standard. In this paper, we firstly present a complete "input target-output parameters" single exposure optimization method for 3D microstructuring utilizing DMD-based grayscale lithography. This numerical optimization based on lithography simulation and sensitivity analysis can automatically optimize a combination of three process parameters for target microstructure; exposure dose pattern, a focal position, and development time. Through a series of experiments using a 20 µm thick positive photoresist, validity of the proposed optimization approach has been successfully verified. Secondly, with the purpose of further advancing accuracy and improve the uniformity of precision for the target area, a multiple exposure optimization method is proposed. The simulated results proved that the multiple exposure optimization method is a promising strategy to further improve precision for thicker photoresist structure.

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One-step 3D shaping using a gray-tone mask for optical and microelectronic applications

Cited by 108 publications

References 1 publication

Double-Exposure Grayscale Photolithography

Double-Exposure Grayscale Photolithography

Cracking pressure control of parylene checkvalve using slanted tensile tethers

Optimization methods for 3D lithography process utilizing DMD-based maskless grayscale photolithography system

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