Boffins develop novel method for creating nanostructured polymer thin films

US researchers at the National Institute of Standards and Technology (NIST) have developed a simple and quick method for making thin films of Block Co-Polymers (BCPs).

Washington, Sept 16 : US researchers at the National Institute of Standards and Technology (NIST) have developed a simple and quick method for making thin films of Block Co-Polymers (BCPs).

BCPs are chemically distinct polymers linked together and have been highly desired by semiconductor manufacturers as patterns of laying down very fine features on microchips, such as arrays of tightly spaced, nanoscale lines.

Annealing certain BCP films - a controlled heating process - causes one of the two polymer components to segregate into regular patterns of nanocylinder lines separated by distances as small as five nanometers or equally regular arrays of nanoscale dots.

Chemically removing the other polymer leaves the pattern behind as a template for building structures on the microchip.

In traditional oven annealing, the quality of the films is still insufficient even after days of annealing.

A process called hot zone annealing - where the thin film moves at an extremely slow speed through a heated region that temporarily raises its temperature to a point just above that at which the cylinders become disordered -has previously been used for creating highly ordered BCP thin films with a minimum of defects but little orientation control.

Now, the NIST team has developed a "cold zone" annealing system, where the polymers are completely processed well below their order-disorder transition temperature.

This, not only eliminates the time and temperature restraints without losing the order yielded by hot zone annealing, the researchers found, but also repeatedly produces a highly ordered thin film in a matter of minutes.

The team further found that the "cold zone" annealing conditions could also control the alignment of the cylinders.

Due to its simplicity, consistent product quality are yielded with virtually no limitations on sample dimensions, the scientists wrote in their research in the September 12 issue of Nano Letters.

Microelectronic companies are currently evaluating the NIST method to fabricate highly ordered sub 30 nm features.

The next step, the NIST researchers say, is to better understand the fundamental processes that make the cold zone annealing system work so well and refine the measurements needed to evaluate its performance.

ANI