Joined: 16 Mar 2004
|Posted: Tue Aug 19, 2008 12:08 pm Post subject: Nanopositioning breaks new record
|Nanopositioning breaks new record
One of the main obstacles facing nanotechnology today is the lack of effective devices for building and characterizing nanoscale structures. For the field to progress, scientists need to be able to control the position of a mechanical system with sub-nanometric accuracy over a moving range of several millimetres. A French team has now taken an important step forward in this direction with the development of a 2D nano-positioning system that can do just this. What's more, the new instrument, based on an interferometric sensor and an optoelectronics board, can be used in a standard atomic force microscope or lithography set-up.
While many modern instruments can move over the millimetre range with nanoscale resolution, their repeatability and accuracy are still larger than tens of nanometres across. These devices are mainly limited by mechanical defects in the translation stage. Indeed, the best positioning device made to date has an accuracy of around 100 nm. This problem could be a serious technological drawback in the near future, especially in photolithography techniques as devices become ever smaller.
Luc Chassagne of the University of Versailles Saint-Quentin and colleagues have made a long-range displacement nanopositioning device that allows a sample holder to move over a long range of millimetres with nanometre scale accuracy – something that has been difficult to achieve until now. The instrument uses an optoelectronic system board that controls the position of a moving mirror with sub-nanometric accuracy. The information on the position of the mirror is determined by comparing the phases of optical beams coming in and out of an interferometer. Finally, there are two translation stages that work in both X and Y directions.
The first stage consists of two linear motors that can move over 50 mm and have a resolution of 10 nm. The second is composed of 2D piezoelectric actuators that can move over 15 µm and has sub-nanometric resolution. This second stage compensates for the defects of the motors in real time and coupling the two ensures accuracy, explains Chassagne.
The system will be useful for all sorts of nanofabrication processes, be they top-down or bottom-up, and any other applications related to nanotechnology, say the researchers.