Nanotechnology; Lithography; 3-dimensional Patterning; Guided Assembly; Scanning Probe Lithography; Polymeric Materials; Stimuli-Responsive Materials; Patterning
Cheong Lin Lee, Paul Philip, Holzner Felix, Despont Michel, Coady Daniel J., Hedrick James L., Allen Robert, Knoll Armin, Duerig Urs (2013), Thermal probe mask-less lithography for 27.5 nm half-pitch Si technology, in Nano Letters
, 13, 4485.
Holzner Felix, Paul Philip, Despont Michel, Cheong Lin Lee, Hedrick James, Dürig Urs, Knoll Armin (2013), Thermal probe nanolithography: in-situ inspection, high-speed, high-resolution, 3D, in Proceedings SPIE
, 8886, 888605-9.
Paul Philip, Knoll Armin, Holzner Felix, Despont Michel, Duerig Urs (2012), Rapid turnaround scanning probe nanolithography, in Nanotechnology
, 22, 275306.
Holzner F., Kuemin C., Paul P., Hedrick J. L., Wolf H., F. Spencer N. D., Duerig U., Knoll A. W. (2011), Directed Placement of Gold Nanorods Using a Removable Template for Guided Assembly, in Nano Letters
, 11(9), 3957-3962.
Paul Philip, Knoll Armin, Holzner Felix, Duerig Urs (2011), Field stitching in thermal probe lithography by means of surface roughness correlation, in Nanotechnology
, 23, 385307.
Holzner F, Paul P, Drechsler U, Despont M, Knoll AW, Duerig U (2011), High density multi-level recording for archival data preservation, in APPLIED PHYSICS LETTERS
, 99(2), 023110.
Structuring of surfaces is at the heart of nano-technology and CMOS-electronics. The quest to continue with Moore’s scaling is fueled by the economic advantages of integrating more func-tionality on a given Si footprint and the performance gain that can be achieved by using overall smaller devices. On the other hand, huge technological problems need to be solved in the not too distant future with regard to the lithographic methods that will be used for making the de-vices. According to the roadmap, high throughput lithography will have to cope with a 20nm feature size in 2017. It is not clear at all, whether optical lithography can be extended towards this scale. Alternatively, electron beam lithography (EBL) is a well established high-resolution technology but it suffers from high cost and through-put problems, in particular writing speeds scale over-proportionally poorly at small scales. As another alternative, nano-imprint lithogra-phy (NIL) has attracted substantial attention more recently. It has been proposed to use the technology for FLASH memory production in the near future. However, NIL requires to-scale fabrication of masters and hence does not solve the fundamental lithographic problem. How-ever, it provides a bridge for closing the gap between slow sequential high resolution lithogra-phy and large scale mass production.In this proposal we address the fundamental lithographic problem of inscribing patterns in organic materials with nano-meter precision using scanning probe methods. Recently, we dis-covered that virtually any arbitrarily shaped structure can be engraved in low molecular weight glasses using a hot tip. The structure is defined by a pixel set. At each pixel, a force and tem-perature stimulus is applied to the probe tip which then induces the evaporation of a controlled amount of organic material. The amount of material and thus the depth and radius of the pixel depend on the applied tip force, the tip temperature and the duration of the stimulus. At the end of the exposure the pixel map has been translated into a topographic image whereby the organic material is thinned down by a well defined distance at each pixel position. The interest-ing feature of the process is that no post development is needed. The finished pattern is ob-tained in the writing step. Direct inspection of the writing can be performed in situ and correc-tive measures can be applied if necessary on the fly. Furthermore, patterning speeds on the order of ?s per pixel can be achieved. Thus the proposed project brings e-beam like patterning capabilities within reach of an ordinary probe microscopy system.The patterned organic material may serve as a 2-dimensional mask similar to a conventional photolithographic resist mask in standard Si processing. 300nm deep trenches separated by 30 nm wide walls have been produced in this way. As an additional important feature, one can also realize 3-dimensional structures by repeating the writing in previously written fields thereby removing another layer of the organic material. The resulting 3-dimensional structures can be used in their native state, for example as templates for replication. More interestingly, the 3-dimensional pattern can also be transferred into other materials by means of anisotropic ion etching whereby the etch selectivity actually provides an amplification mechanism for the depth scale. The work to be performed in this proposal addresses three fundamental issues:(1) Technological benchmarking and scaling limits: The goal is to understand the prospects and limitations of the technique. In particular, it is important to develop a thorough physical un-derstanding of the key processes involved. This forms the basis for directed research towards process optimization in the future.(2) Materials science: The initial experiments were done using a phenolic molecular glass with a molecular weight of 715 Da. According to our current thinking, hydrogen cross-linking due to the OH groups is the differentiator for thermo-dissociation patterning. Thus, the material selec-tion is wide open. From an application point of view, Si containing molecular glasses are par-ticularly interesting because of their etch specificity. Thermo-dissociation also works for spe-cifically tailored polymers as we have been able to demonstrate in the past two months. This opens up new perspectives by using block-copolymers for obtaining organic films with a high degree of order. We envisage that extreme resolution and patterning fidelity might be obtained in such ordered films.(3) Having gained a thorough understanding of the patterning capabilities, textured substrates for novel bottom-up approaches will be investigated. This work aims at closing the link towards guided self assembly, which is seen as a promising route for implementing radically new nano-technological schemes, in particular also in the life sciences. Here we specifically exploit the feature of extending the patterning capabilities to the third dimension.