&lt;title&gt;Proximity printing by wave-optically designed masks&lt;/title&gt;

Wyrowski, Frank; Kley, Ernst‐Bernhard; Buehling, Sven; Nellissen, Ton J.M.; Wang, Lingli; Dirkzwager, Maarten

doi:10.1117/12.451293

Cited by 8 publications

(4 citation statements)

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“…For dense routing (equal track and gap width) it will be necessary to abandon the analytical cylindrical lens equation and instead use more direct computational methods. Our present analytical CGH computation method can make no use of the measured photoresist response function, but the application of iterative methods may enable process latitude to be improved, as has been done for planar substrates [5]. This is similar to the growing field of inverse lithography [20], but for 3D substrates.…”

Section: Discussionmentioning

confidence: 95%

“…Diffraction cannot be avoided-it is a fundamental physical law, but attempts can be made to account for its effects on the photolithographic process. High-resolution features have been patterned onto planar substrates at a 50 μm exposure gap by utilizing phase/amplitude masks designed using an iterative method [5]; however, the method requires an elaborate mask making procedure and only applies to planar substrates. Our 3D holographic lithography technique has been developed to address the line distortion issues encountered when patterning non-planar substrates [6].…”

Section: Introductionmentioning

confidence: 99%

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Controlled-width track in through silicon via using 3D holographic photolithography with modified electrodepositable photoresist

Toriz-Garcia¹,

Williams²,

McWilliam³

et al. 2009

J. Micromech. Microeng.

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We present a novel lithographic process for patterning controlled-width tracks onto anisotropically micromachined silicon. The technique is based on the use of computer-generated holographic masks with a custom alignment and exposure tool. Experimental and simulation results are presented. 3D holographic photolithography significantly reduces the problem normally present with photolithography on non-planar surfaces-namely diffractive line broadening. A negative-acting electrodepositable photoresist (InterVia 3D-N) is used in the study. Its deposition onto the 3D substrate is optimized by modification of coating temperature and thickness and of pre-exposure bake conditions. We show the successful patterning of a constant-width 8 μm line down the sloping sidewall of a 500 μm thick silicon wafer. This is beyond the conventional resolution limit and indicates the potential of the technique for realizing high-density vertical routing in electronic packages and MEMS.

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Section: Discussionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Controlled-width track in through silicon via using 3D holographic photolithography with modified electrodepositable photoresist

Toriz-Garcia¹,

Williams²,

McWilliam³

et al. 2009

J. Micromech. Microeng.

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“…This is often implemented as the Gerchberg-Saxton algorithm [3], involving successive reduction of errors appearing within the reconstruction when imposing the phase-only restriction in the CGH. There are examples of high-quality reconstructions being achieved by error reduction methods based on iterative Fourier transform methods (IFTMs) [4] including generation of nonplanar patterns [5]. While many refinement methods exist [6], limitations remain concerning the handling of "Manhattan" geometry patterns composed of lines that intersect and abut one another.…”

Section: Introductionmentioning

confidence: 99%

High-contrast pattern reconstructions using a phase-seeded point CGH method

McWilliam¹,

Williams²,

Cowling³

et al. 2016

Appl. Opt.

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A major challenge encountered in digital holography applications is the need to synthesize computer-generated holograms (CGHs) that are realizable as phase-only elements while also delivering high quality reconstruction. This trade-off is particularly acute in high-precision applications such as photolithography where contrast typically must exceed 0.6. A seeded-phase point method is proposed to address this challenge, whereby patterns composed of fine lines that intersect and form closed shapes are reconstructed with high contrast while maintaining a phase-only CGH. The method achieves superior contrast to that obtained by uniform or random seeded-phase methods while maintaining computational efficiency for large area exposures. It is also shown that binary phase modulation achieves similar contrast performance with benefits for the fabrication of simpler diffractive optical elements.

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“…A phase shift mask can be considered a diffractive optical element capable of modulating both phase and amplitude (or intensity) of an incoming light wavefront (21)(22)(23). The resolution of a system operating in proximity mode can be dramatically improved by replacing the conventional photomask with a mask able to compensate these diffraction effects (23)(24)(25).…”

Section: Introductionmentioning

confidence: 99%

Phase-Shift Photomask Designed by Scalar Diffraction Theory

Cirino

Mansano

Verdonck³

et al. 2009

ECS Trans.

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This work describes the design of a phase shift lithographic photomask for operation in proximity printing mode. The design explores the freedom of the diffraction of light by travelling along the distance between the mask plane and the wafer plane. To this end, a phase and amplitude modulation distributions was generated, which have to be used in the fabrication of the proposed photomask. Then a photomask with test structures containing several geometric features was fabricated. It is able to modulate both phase and amplitude of the incoming wavefront during exposure of a wafer. The lithographic image to be patterning must be projected onto the wafer plane, located at a distance of 50 µm behind the mask. The 50 µm gap is a necessary condition to explore the diffraction of light in order to improve the resolution when compared with traditional binary masks in proximity printing mode.

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<title>Proximity printing by wave-optically designed masks</title>

Cited by 8 publications

References 0 publications

Controlled-width track in through silicon via using 3D holographic photolithography with modified electrodepositable photoresist

Controlled-width track in through silicon via using 3D holographic photolithography with modified electrodepositable photoresist

High-contrast pattern reconstructions using a phase-seeded point CGH method

Phase-Shift Photomask Designed by Scalar Diffraction Theory

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