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HL: Fachverband Halbleiterphysik

HL 3: Preparation and Characterization

HL 3.2: Vortrag

Montag, 22. März 2010, 10:30–10:45, H14

Focused ion beam lithography for rapid prototyping of metallic films — •Patrick Osswald, Josef Kiermaier, Markus Becherer, and Doris Schmitt-Landsiedel — Lehrstuhl für Technische Elektronik, TU München, Munich, Germany

We present FIB-lithography methods for rapid and cost-effective prototyping of metal structures covering the deep-submicron- to the millimeter-range in a single lithography cycle.

Focused ion beam (FIB) systems are widely used in semiconductor industry and research facilities for both analytical testing and prototyping. A typical application is to apply electrical contact to micron-sized sensors/particles by FIB induced metal deposition. However, as for E-beam lithography, patterning times for large area bonding pads are unacceptably long, resulting in cost-intensive prototyping.

In this work, we optimized FIB lithography processing for negative and positive imaging mode to form metallic structures for large-areas down do the sub-100 nm range. For negative lithography features are defined by implanting Ga⁺-ions into a commercial photo resist, without affecting the underlying structures by impinging ions. The structures are highly suitable for following lift-off processing due to the undercut of the resist.Metallic feature size of down to 150 nm are achievable. For positive lithography a PMMA resist is exposed in FIB irradiation. Due to the very low dose (3·10¹² ions/cm²) the writing time for an e.g. 100 µ m x 100 µ m square is approx. 15 seconds. The developed resist is used for subsequent wet chemical etching, obtaining a 100 nm resolution in metal layers.