The development is due to be discussed at the 22nd International Microprocesses and Nanotechnology Conference being held at the Sheraton Sapporo Hotel, Sapporo, Japan on Nov. 19.

Polymer-based photoresists are expected to hit problems at the 20-nm generation of processes due to like of resolution, as are the argon fluoride deep ultra violet laser lithography systems, currently in use. EUV lithography equipment has been extensively researched but must be accompanied by appropriate resists and other infrastructure developments, such as pellicles. Toshiba has developed a molecular resist for EUV lithography by employing a derivative of truxene, a low molecular weight material that is finer and more durable than currently used polymer materials. Semiconductor circuit patterning requires photoresists that can be used in both positive-tone and negative-tone processes to secure precise structuring.

Toshiba is due to report how it has now succeeded in applying it to the more demanding task of the negative tone process forming a test pattern with 22-nm line widths. The truxene derivative is said to show 40 percent more etch-durability than the conventional polymer resist polyhydroxystyrene.

Toshiba said it has balanced the truxene derivative with a cross-linking material to maximize the negative photoresist performance. The cross-linker and a photo-acid-generator are required to connect the molecules through a chemical reaction, and their compound ratio was optimized according to the transmittance of the light and reaction speed. Toshiba has found that the optimized ratio for truxene derivative to cross-linker is three to one.

Toshiba said it would improve the performance of the molecular resist and apply it to chip manufacture. According to the International Technology Roadmap for Semiconductors, high volume production of this generation is expected to start in 2013.

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