Advanced mask aligner lithography (AMALITH)

Abstract

In this paper we show that it is possible using optical photolithography to obtain micron and submicron features for periodic structures in non-contact using the Talbot effect. In order for this effect to work it is important to have good control of the illumination light and here we show that the MO Exposure Optics (MOEO) developed by SUSS MicroOptics provides uniform and well collimated illumination light suitable for Talbot lithography. The MOEO can easily be incorporated into a standard mask aligner. Here we show 1µm and 0.65µm diameter holes in a hexagonal array in photoresist made in large-gap proximity printing.

Talbot lithography as an alternative for contact lithography for submicron features

“…The second Köhler integrator ensures uniform illumination of the mask. Although there are other advantages of the MOEO for mask aligners (see www.sussmo.ch/), for integrated Talbot photolithography the key features of the MO exposure optics are that it has excellent light uniformity (+/-2%), and that the illumination angle of the light can be chosen [7]. The basic mechanics of a Köhler integrator is the imaging of a first array of sub apertures by the corresponding lenses of the second array.…”

“…The Talbot distance depends on the type of pattern, the periodic length of the pattern and the wavelength of the illumination light; the effect was first described mathematically by Rayleigh in 1881 [2]. There has already been some work published on Talbot lithography [3][4][5][6][7] including a recent paper by Case et al [8] which gives a very clear explanation of this phenomenon, an example of which is shown in Figure 1.…”