Double-Exposure Grayscale Photolithography

Mosher, L. A.; Waits, C.M.; Morgan, Brian; Ghodssi, Reza

doi:10.1109/jmems.2008.2011703

Cited by 41 publications

(15 citation statements)

References 38 publications

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“…The grayscale lithography is achieved via dose modulation for patterning the photonic device with vertical resolution of B10 nm. Note that although similar processes are employed in the fabrication of diffractive optical elements, micro-electro-mechanical structures and lower contrast gradedindex lenses [21][22][23][24][25] with relatively weak height variations of 80 nm over distances of tens of microns, in our case, the process enables strong height variations of 400 nm over less than 1 mm while maintaining precise control of both the resist height profile on the nanometre scale. Figure 3 shows the grayscale patterned device with a smooth surface profile in Si.…”

Section: Resultsmentioning

confidence: 99%

On-chip transformation optics for multimode waveguide bends

et al. 2012

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Current optical communication systems rely almost exclusively on multimode fibres for short-and medium-haul transmissions, and are now expanding into the long-haul arena. Ultra-high bandwidth applications are the main drive for this expansion, based on the ability to spatially multiplex data channels in multimode systems. Integrated photonics, on the other hand, although largely responsible for today's telecommunications, continues to operate almost strictly in the single-mode regime. This is because multimode waveguides cannot be compactly routed on-chip without significant inter-mode coupling, which impairs their data rate and prevents the use of modal multiplexing. Here we propose a platform for on-chip multimode devices with minimal inter-mode coupling, opening up the possibilities for integrated multimode optics. Our work combines a novel theoretical approach-large-scale inverse design of transformation optics to maximize performance within fabrication constraints-with unique grayscale-lithography fabrication of an exemplary device: a low-crosstalk multimode waveguide bend.

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Section: Resultsmentioning

confidence: 99%

On-chip transformation optics for multimode waveguide bends

et al. 2012

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“…Theoretical calculation 13 presents that three dimension (3D) periodic structures show an extremely obvious enhancement effect on the LEDs light extraction efficiency. Meanwhile, the low throughput or high cost are associated with the techniques such as the direct laser writing, 14,15 the laser interference lithography, 16 and gray exposure, 17,18 which limits the large-scale industrial production. As we know, the large area and uniform microstructures can be obtained by ultraviolet (UV) or extreme ultraviolet (EUV) lithography with low cost and high throughput.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of large-scale spherical-cap structure and the application on n-GaN based light-emitting diodes

Yin

Zhu

Shen

et al. 2014

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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An under exposure method based on Fresnel diffraction effect in a conventional optical lithography system is used to fabricate large-scale, uniform spherical-cap structures. This method provides an effective roughening technology on the top surface of light-emitting diodes (LEDs) to improve the light extraction efficiency of LEDs. LEDs with high duty cycle spherical-cap structures showed enhanced light output power by 130%-160% compared with the LED with a flat surface. This simple and easy shape control method has potential applications in other optical devices such as organic LEDs, inorganic solar cells, and laser diodes. V

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“…Depending on the properties of the photoresist and available exposure dose values, different structure depths (also called grey levels) can be achieved. For achieving greyscale structures, several photolithography methods like multiple-step exposure, pixelated mask exposure and direct writing can be used [1].…”

Section: Introductionmentioning

confidence: 99%

Process development for 3D laser lithography

Kaste¹,

Filbert

Mescheder

et al. 2014

WIT Transactions on the Built Environment

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The field of micro-electro-mechanical-systems (MEMS) grew out from the integrated circuit (IC) industry. So far the main fabrication techniques used in MEMS are planar technologies, which set limitations to the sensor/actuator design. Therefore greyscale (3D) technology seems to be the method for fabrication of three-dimensional structures in a single lithography and etching step. The idea in fabricating a 3D photoresist structure is the controlled transmission of UV light intensity during the exposure process. The result of this work is to provide a preliminary process solution for the formation of nearly arbitrarily shaped 3D forms in photoresist using Heidelberg Instrument DWL 66FS direct writing lithography tool. For this purpose, the investigation results of the exposure tool possibilities of the photoresist selection for 3D applications and as a real greyscale application, slopes with different angles, which will be used for making a tactile sensor, are provided.

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Double-Exposure Grayscale Photolithography

Cited by 41 publications

References 38 publications

On-chip transformation optics for multimode waveguide bends

On-chip transformation optics for multimode waveguide bends

Fabrication of large-scale spherical-cap structure and the application on n-GaN based light-emitting diodes

Process development for 3D laser lithography

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