Literature review for open hardware project on Mask Aligner

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Literature review : Mask Aligner[edit | edit source]

Background[edit | edit source]


  • Google search for Mask Aligner
  • Wikipedia

Mask Aligner/Aligner[edit | edit source]


  • "An aligner, or mask aligner, is a system that produces integrated circuits (IC) using the photolithography process. It holds the photomask over the silicon wafer while a bright light is shone through the mask and onto the photoresist. The "alignment" refers to the ability to place the mask over precisely the same location repeatedly as the chip goes through multiple rounds of lithography."

History[edit | edit source]

  • There are several types of mask aligners. The early contact mask aligners placed the mask in direct contact with the wafer but doing so would damage the substrate. The proximity mask aligners held the mask slightly above the substrate to avoid the damage but doing so made it difficult to work on manually. The projection mask aligners that was introduced by Perkin-Elmer in 1973 held the mask separately from the chip and this made the adjustment of the image much easier.
  • MEMS and Nanotechnology Exchange
  • Layout and Mask Conventions

Market Survey[edit | edit source]

Need costs and capabilities
  • SUSS Microtec is one of the largest manufacturers of mask aligners. They promise high alignment accuracy, superior quality, and sophisticated exposure optics. SUSS MicroTec design their mask aligners for lithography applications like in the field of 3D packaging, MEMS, LED, compound semiconductors, power devices, photovoltaic, nanotechnology, and wafer-level optics.
  • The three major automated mask aligner is MA300 Mask Aligner, MA200 GEN3 Mask Aligner, and MA 100/150E GEN2 Mask Aligner.

List of References[edit | edit source]

A Compact Low-Cost Low-Maintenance Open Architecture Mask Aligner for Fabrication of Multilayer Microfluidics Devices [edit | edit source]

Quang Long Pham, Nhat-Anh N. Tong, Austin Mathew, Roman S. Voronova

A custom-built mask aligner (CBMA), which fundamentally covers all the key features of a commercial mask aligner, while being low cost, lightweight, and having low power consumption and high accuracy is constructed. The CBMA is comprised of a custom high fidelity LED light source, vacuum chuck and mask holder, high-precision translation and rotation stages, and high-resolution digital microscopes.

Keywords: mask aligner, photolithography, microfluidics, microfabrication, multi-height

A simple mask aligner and printing frame for conformable photomask lithography [edit | edit source]

B. Smilowitz ; R.J. Lang

Conformable photomask lithography allows submicrometer lines to be replicated by contact printing. Surface acoustic wave devices with 0.4-µm lines have been produced using this technique. A mask aligner and printing frame have been designed which feature micrometer controlled X and Y motion, rotation about the center of the viewing field, and both top and bottom illumination of mask and substrate. The construction and use of the apparatus, which is based on a toolmaker's microscope, is fully described.

Creating a Mechanical Mask Aligner workaround to be used with Photolithography [edit | edit source]


A machine like that would be very useful for research purposes due to the uses of photolithography in micro builds and circuits. The purpose of this MQP was to build a mechanical workaround for the old mask aligner system and allowing the machine to be revived in the future.

The holographic mask aligner[edit | edit source]

Published in: 1993 Fourth International Conference on Holographic Systems, Components and Applications S. Gray, F. Clube, D. Struchen INSPEC Accession Number: 4577690

Total internal reflection holography has successfully been implemented into an exposure tool for microlithography. The operation of this system, the world’s first holographic mask aligner, is described, and the key components (focus, alignment, and the holographic mask) are discussed.

A novel shadow mask aligner based on three points levelling for wedge error compensation[edit | edit source]

Pankaj B Agarwal, Deepak Kumar Panwar, Bijendra Kumar, and Ajay Agarwal : Engineering Research Express, Volume 2, Number 1

This paper reports a novel shadow mask aligner, which is capable of aligning planar with ~1 μm alignment error as well as provision to compensate the wedge error by using movements of three precision linear actuators, spotted under an optical microscope. The use of three points leveling also overcomes the common error of the upper assembly bending, which could occur with time after its continuous use.

Mask aligner lithography simulation - From lithography simulation to process validation[edit | edit source]

K.Motzek, S.Partel, A.Bramati, U.Hofmann, N.Unal, M. Hennemeyer, M.Hornung, A.Heindl, M. Ruhland, A.Erdmann, P.Hudek

  • This paper compares the result between simulated and experimental results where the authors investigate the predictive qualities of lithography simulation. And this is done by using a properly calibrated photoresist model. The dissolution rate monitors are proved to be an excellent tool to calibrate the development models.
  • The paper also demonstrated the progress that can be made in lithography simulations when the mask aligner illumination system is combined with accurate modeling of photoresist development.
  • The data obtained from the experiments and simulations show that lithography simulation can replace test exposure series in the cleanroom.

High Intensity UV-LED Mask Aligner for Applications in Industrial Research [edit | edit source]

Katrin Schindler, U. Leischner, P. Kaiser, T. Striebel, U. Schömbs, C. Lopper

This paper presents results on a semi-automatic mask aligner with UV-LED illumination, SUSS MA/BA8 Gen4 Pro equipped with a UV-LED lamp house and MO Exposure Optics [8]. The tool offers a customer-controllable spectrum with three wavelengths corresponding to the mercury i, g and h-line. The field-proven MO Exposure Optics guarantees a reliable smooth angular spectrum that can be fully customized. Full 8 inch wafers were exposed with the same high intensity and light uniformity as with standard 1 kW mercury lamps. Broadband and single line exposures were performed on several standard processes. The resolution and appearance of the produced features compared well to traditional exposures with a mercury lamp. In addition an analysis of the eco-fingerprint of UV-LED-lithography system is presented. For a semi-automatic system used under typical research institute conditions the LED light source can survive a machine life-time. LEDs don´t require warm up times and thus are switched on during exposure only. Moreover, low power consumption of the LEDs during operation and no need for nitrogen flow cooling also contribute to very low running cost and a green footprint. In summary, the lithography industry will greatly benefit from UV-LED illumination paving the way for future process innovations in a mercury-free and safe environment.

Fine pattern lithography for large substrates using a holographic mask aligner[edit | edit source]

A.R.Nobari, S.Gray, F.Clube, D.Struchen, S Malfoy, N. Magnon, B.Le. Gratiet

  • The paper focuses on the fine pattern of lithography techniques for large substrates using a holographic mask aligner. The holographic mask aligner has a imaginf resolution of 0.5 micrometers and an exposure field of 250 X 300 mm. This system also offers substrates up to 370 X 470 mm.
  • The holographic mask aligner has a high resolution and offers step-free lithography.

Contact and proximity lithography using 193nm excimer laser in mask aligner [edit | edit source]

S. Partel, S. Zoppel, P. Hudek, A. Bich, U. Vogler, M. Hornung, R. Voelkel

  • This paper describes the use of Excimer laser lithography in a mask aligner where the DUV light from the Excimer laser is homogenized using a micro lens. This paper also compares the conventional homogenization optics (the MO exposure optics) the improved illumination uniformity which is calculated 1.8% for MO exposure optics and 2.9% for the A-optics.
  • As compared to the A optics the effect of Mo exposure optics shows improvement in the patterning of layouts containing critical dimensions down from 8 micrometers to 2 micrometers.

Resolution enhancement for advanced mask aligner lithography using phase-shifting photomask [edit | edit source]

T. Weichelt, U. Vogler, L. Stuerzebecher, R. Voelkel, and U. D. Zeitner

Abstract : The application of the phase-shift method allows a significant resolution enhancement for proximity lithography in mask aligners. Typically a resolution of 3 µm (half-pitch) at a proximity distance of 30 µm is achieved utilizing binary photomasks. By using an alternating aperture phase shift photomask (AAPSM), a resolution of 1.5 µm (half-pitch) for non-periodic lines and spaces pattern was demonstrated at 30 µm proximity gap. In a second attempt a diffractive photomask design for an elbow pattern having a half-pitch of 2 µm was developed with an iterative design algorithm. The photomask was fabricated by electron-beam lithography and consists of binary amplitude and phase levels.

Advanced mask aligner lithography (AMALITH) for thick photoresist [edit | edit source]

Reinhard Voelkel, Uwe Vogler, Arianna Bramati, Marc Hennemeyer, Ralph Zoberbier, Anja Voigt, Gabi Grützner, Nezih Ünal & Ulrich Hofmann

Advanced mask aligner lithography (AMALITH) is a holistic approach to improve shadow printing (contact and proximity lithography) in mask aligners. AMALITH is based on two tools, the MO Exposure Optics®, a new illumination system allow shaping the angular spectrum of the illumination light, and LAB, a software tool for full 3D simulation of the shadow printing process. MO Exposure Optics® is provided by SUSS MicroTec AG (, as an upgrade for all current and older mask aligner models. MO Exposure Optics® decouples the illumination from lamp misplacement (self-calibrated light source), improves the light uniformity, provides telecentric illumination and enables customized illumination in mask aligners. LAB is a software tool provided by GenISys GmbH (, and allows simulating the complete chain from illumination, mask pattern, photoresist and resist processing. The combination of both tools allows optimizing mask aligner lithography beyond today’s limits.

Advanced mask aligner lithography: new illumination system [edit | edit source]

Reinhard Voelkel, Uwe Vogler, Andreas Bich, Pascal Pernet, Kenneth J. Weible, Michael Hornung, Ralph Zoberbier, Elmar Cullmann, Lorenz Stuerzebecher, Torsten Harzendorf, and Uwe D. Zeitner

A new illumination system for mask aligner lithography is presented. The illumination system uses two subsequent microlens-based Köhler integrators. The second Köhler integrator is located in the Fourier plane of the first. The new illumination system uncouples the illumination light from the light source and provides excellent uniformity of the light irradiance and the angular spectrum. Spatial filtering allows to freely shape the angular spectrum to minimize diffraction effects in contact and proximity lithography. Telecentric illumination and ability to precisely control the illumination light allows to introduce resolution enhancement technologies (RET) like customized illumination, optical proximity correction (OPC) and source-mask optimization (SMO) in mask aligner lithography.

Specification of TAMARAK 152 Mask Aligner [edit | edit source]

Reference : University of Memphis

In this article we can find complete specification of a TAMARAK 152 mask aligner.