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R&D Topics / Topic: Micro and Nanometer Structures
Ion- and laser-stimulated processes for patterning and structuring
Within this research topic basic research on beam assisted surface patterning of application relevant materials, thin films or multilayers by means of ion and laser beams are investigated with the aspects of identifying the process-governing chemical and physical mechanisms. Basically the methods of pattern transfer by ion etching and direct surface patterning by laser beams are studied alternatively and supplementary.
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Fig. 1: Schematic comparison of pattern transfer and direct patterning processes.
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The common aim of the process studies on ion, plasma and laser patterning are the development of low damage, high quality techniques for patterning materials for applications in the fields of the micro- and nano technologies such as (micro/nano) optics, photonics, analytics, and optoelectronics. Therefore, the main goals are: (i) the reduction of the lateral dimensions of patterns below 100 nm, (ii) the enhancement of the pattern precision in depth size and roughness, and (iii) the reduction of remaining process-induced material alterations.
Fig. 2: Cross section of typical surface topographies fabricated by the mentioned patterning processes.
The work on direct patterning/structuring of surfaces and materials by pulsed laser radiation concentrates on the study of the involved processes and mechanisms, the development of appropriate conditions and parameters and to develop new processing approaches. At the IOM preferentially innovative pulsed laser sources such as ns-UV as well as ultrashort (fs) IR lasers are exploited because these sources enable innovative solutions of the addressed aims.
The main research areas on laser patterning/structuring are:
- laser-induced backside etching processes of transparent materials
- ultrashort pulse laser ablation and scribing of thin films
- ultrashort pulse laser interactions with solid surfaces
- beam shaping, mask projection and machining techniques for laser beam patterning.
Fig. 3: Examples for direct patterning with laser beams for the fabrication of micro and sub-micro patterns and structures.
In consequence of the international tendency towards smaller functional structures and patterns of below 50 nm and the enhanced demands on the precision of the transfer process and the accuracy of the depth requires improved processes and technologies for electron beam writing and the transfer of electron beam written masks into functional materials. Within this scope two linked complexes of problems have to be solved: (i) the e-beam writing of etch-stabile mask patterns with appropriate dimensions, edge roughness, and thickness and (ii) the tuning and improvement of the etching process to transfer such mask patterns into functional materials with sufficient depth and perpendicular etch walls. Thus, both processes are combined developed with consideration of the material properties of the mask and the physical/chemical interaction of the reactive ion beam at the materials surface.
Main fields of research in ion beam pattern transfer are:
- study of reactive- and chemical-enhanced ion beam etch processes (RIBE/CAIBE)
- developing of processes and study of parameters for highly selective and high quality pattern transfer
- investigation of proportional transfer processes into optical materials
- developing electron beam writing techniques for highly resistant masks for RIBE/CAIBE processes
- beam shaping and mask projection techniques for micro structuring.
Fig. 4: Examples for the pattern transfer by dry etching for micro and nano structures.
Selected Publications
- K. Zimmer, R. Böhme, D. Ruthe, B. Rauschenbach, The influence of laser-induced surface modifications on the backside etching process, Appl. Surf. Sci. 253 (2007) 6588-6594.
- K. Zimmer, A. Braun, Excimer laser machining for 3D-surface structuring, in A. Peled (Ed.) Photo-Excited Processes, Diagnostics and Applications, Kluwer Academic Publishers, Boston (2003) 325.
- K. Zimmer, R. Böhme, A. Braun, B. Rauschenbach, F. Bigl, Excimer laser-induced etching of sub-micron surface relief gratings in fused silica using phase grating projection, Appl. Phys. A 74 (2002) 453-456.
- R. Böhme, D. Spemann, K. Zimmer, Surface characterization of backside-etched transparent dielectrics, Thin Solid Films 453 (2004) 127.
- J. Dienelt, J. von Sonntag, K. Zimmer, B. Rauschenbach, Structuring of GaAs. I. Chemical dry etching: Temperature und chlorine pressure dependence of etch rates, J. Vac. Sci. Technol. B 22(4) (2004) 1964-1969 .
- J. Dienelt, K. Zimmer, J. von Sonntag, B. Rauschenbach, C. Bundesmann, Roughness and damage of a GaAs surface after chemically assisted ion beam etching with Cl2/Ar+, Microelectron Eng 78-79 (2005) 457-463.
- Frederico Canova, Raphael Clady, Jean-Paul Chambaret, Manuel Flury, Svtelen Tonchev, Renate Fechner, and Olivier Parriaux, High-efficiency, broad band, high-damage threshold high-index gratings for femtosecond pulse compression, Optics Express Vol. 15, Issue 23 (2007) 15324-15334.
Contact
Dr. Klaus Zimmer
Phone: +49 (0)341 235-3287,
email:
klaus.zimmer (at) iom-leipzig (dot) de
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