The Effect of Adsorbed Cationic Surfactant on the Pattern Collapse of Photoresist Lines in Photolithographic Processes

摘要

A crucial problem in the manufacturing of high aspect ratio structures in the microchip production is the collapse of photoresist patterns caused by unbalanced capillary forces. A new concept to reduce the pattern collapse bases on the reduction of the capillary forces by adsorption of a cationic surfactant. The application of a cationic surfactant rinse step in the photolithographic process leads to a reduction of the pattern collapse. Physico-chemical investigations elucidate the mechanism of surfactant adsorption and its effect on the surface properties of the photoresist. It is shown that the best pattern collapse reduction is obtained at a surfactant concentration referring to monolayer coverage. In this concentration range the capillary forces are minimized due to a hydrophobizing of the processed photoresist by adsorbed cationic surfactant.