Reliability of wet chemical etching of silicon (TPC.5990)

Research
Bulk Micromachining refers to machining of monocrystalline silicon wafers. The most important technology is wet chemical anisotropic etching, where the dependence of the etch rate on the crystallographic orientation of the silicon is exploited. This is nowadays a key technology for the fabrication of miniature sensors (pressure, crash, flow, angular rate.) and other microsystems (ink jet printer head, filters, resonators for radio frequency applications, valves, pumps, opto-mechanical connectors.). Although widely applied, the precision this technology offers is still insufficient for many applications, for example in the dimensions of the ink channels in ink jet printers, which broadly define the droplet size. The technology also suffers from inadequate reproducibility, which prevents its application in many promising areas. It is the problems associated with the reproducibility of the etch rate, the emergence of defects, the surface finish and roughness of features that will be addressed in this project. These problems, which are related to the details of the interaction of the solid surface with the etching solutions, will be studied by surface examination using optical and atomic force microscopy, electrochemistry and theory.

Utilisation
Finding solutions to these problems of precision and reproducibility is challenging on both a scientific and a technological level. It will widen the applicability of micromachining in many areas, such as high precision mechanical sensors, ink jet printing channels, vials, V-grooves for precision alignment of optical components, blades and utimately in nanotechnology.

More information can be found on the websites of the participating research groups:

• University of Twente: Transducers Science and Technology Group
• Utrecht University: Condensed Matter and Interfaces
• Radboud University Nijmegen: Solid State Chemistry

Five companies are involved in this project.