Advanced ultraviolet cross-link process and materials for global planarization

Abstract

The use of conventional thermal cross-link materials such as negative resists, antireflective coating, and planarizing layers does not lead to excellent planarization for multilevel interconnects and specially via arrays prior to trench patterning for an advance lithography. The large thicknesses bias between the blanket areas and interconnect areas, and between the blanket areas and via arrays are usually observed. Large thickness bias creates problems during next lithography by narrowing the process latitude. Recently, chemical mechanical polishing (CMP) technology has been proposed to achieve the planarization. However, CMP planarization technique is very sensitive to pattern density, and there is a strong possibility that chemical etching reaction will increase the dielectric constant. The current CMP technique still requires a new investment in the equipment. We report another novel approach for global planarization using UV cross-link material (XUVTM) and the dielectric UV exposure unit in coater equipment (Clean Track). This planar technique provides benefits for reducing the thickness bias observed in the 22- to 65-nm generation lithography and imprint processes. Using this technique, XUVTM TNG076 has achieved global planarization of 10-nm thickness bias in 85-nm diameter via topography when the blanket film thickness was only 110 nm.