Due to the explosive growth of the semiconductor industry, various processing techniques for working with silicon (Si) as a substrate material have been developed and successfully established by the semiconductor industries.
Now Si is being used for producing small-scale mechanical components of the size of only a few microns (10-6m) or even less. The processing techniques are being adopted from the semiconductor processes and further developed for the means of achieving small and reliable structures. The possible applications for such micromechanical devices are countless, and are already being used by the aerospace and automotive industries for pressure sensors and accelerometers. With improvements in processes that allow cheaper mass production of the structures, micromachined components will get more and more important, possibly resulting in a technical revolution when formerly impossible structures can come possible.
Figure 1: Example for a micromachined gear for the conversion of rotational
motion to linear
motion15
With the means of microengineering the following aims can be achieved:
- The ability to produce smaller, lighter, and faster versions of existing mechanical devices, with increased dimensional accuracy, e. g., micromotors.
- The production of sensors that rely on changes in silicon's electro-mechanical properties in response to exterior parameter changes such as temperature, pressure, acceleration or humidity
- The adoption of processing techniques well known from the semiconductor fabrication for the cost-effective and efficient production of micromechanical devices
- The use of batch processing for the production of large numbers of identical products in mass fabrication, resulting in a drop in the cost per unit
- The possibility to include technologies and materials not applicable to microelectronics, but which offer certain advantages to micromechanical devices.
A new approach in this field consists in combining highly integrated electronic and mechanical parts together, resulting in so called "Microelectromechanical Systems" (MEMS). This is the next logical step in this process of development and offers a variety of new products.
The most cost-effective way for producing MEMS structures would be to do the processing for the semiconductor (active) part and the micromechanical part on the very same wafer without the need of later assembling of different parts produced separately. Not many experiments in this sector have been made so far and it is to prove whether the IC process and the one used for the mechanical parts are compatible to each other in each case. This report's aim is to provide detailed information on the steps of the production of mechanical structures used for the assembly of high frequency circuits that can possibly be combined with active parts on the same wafer.