In the near future it will be more and more important to produce real nanometer-sized structures for semiconductor devices (e.g., quantum dot lasers) but also for nano-biomechanical applications like the so-called total analysis system implemented on one chip.
We describe here a technique to create nanometer-sized structures in semiconductors and metals by the use of self-assembling diblock copolymers as nano-lithographic masks. Semiconductor quantum structures with very high aspect ratio of 1:10 were fabricated from III-V semiconductor heterostructures by anisotropic dry etching. In a first step, so-called diblock copolymer micelles were generated in a toluene solution. These micelles were loaded by a noblemetal salt. With a “Langmuir Blodgett” technique we can decorate complete wafers with a monolayer of highly ordered micelles, covering almost the complete surface. After treatment in a hydrogen plasma all of the organic components are removed and only crystalline metal clusters of ~12 nm size remain. This metal cluster mask can be used directly in a highly anisotropic chlorine dry etching process to etch cylinders in GaAs and its In and Al alloys. It is also possible to etch through a quantum well layer underneath the surface in order to produce quantum dots.
By evaporating metals and applying a wet chemical image reversal process, we can invert the etched structure and generate a gauzy gold film with nano-holes inside. It is thinkable to use this porous gold film as a nano-filter in upcoming nano-biotechnology applications.