INVESTIGATION OF THE NOTCHING EFFECT FOR SINGLE-LAYER DEEP-ULTRAVIOLET RESIST PROCESSING

In order to extend the application limit of single layer resist proces sing to 0.25 mu m pattern formation, the influence of resist thickness on reflective notching effects was investigated, using a two-dimensio nal resist profile simulator with the vector model. As the resist thic kness increased, the reflective notching was varied periodically. Resi st profile degradation due to reflective notching was maximum at the r esist thickness where resist sensitivity was maximum (E-max), and was minimum at the resist thickness where resist sensitivity was minimum ( E-min). The reflective notching was strongly dependent on the effectiv e exposure dose E-eff at the bottom of the resist film, defined as the product of resist transmittance and optimum exposure dose E-opt. Thes e simulation results were verified experimentally. It was concluded th at the resist thickness should be set to minimize exposure dose for th e reduction of reflective notching effects. (C) 1997 American Vacuum S ociety.