Optimization of bottom antireflective coating materials for dual damascene process

The "via first - trench second" dual damascene technology is currently being explored by several major semiconductor manufacturers due to lithography constraints of printing small contacts on extremely non-planar topology (trench first technology). Typical via holes are 0.30-0.50 mu m and 0.18-0.25 mu m with aspect ratios of 3 to 6 for i-line and DUV exposures, respectively. The novel approach utilizes an organic material to fill via holes to a desired level with some planarization of the topographic pattern. Numbers of novel polymers have been synthesized and evaluated to fulfill the requirements for the dual damascene process. These polymers showed good coating and planarizing properties. By modifying the formulations such as polymer molecular weight, viscosity, solvents, and cross linker and thermal acid generator additives, as well as dispense and casting process conditions, the polymers were able to fill the via holes in 20 to 80% with good fill profile. Further, these polymers were incorporated with chromophores, which are highly absorptive at 365nn and 248nm wavelength. Similar to the bottom antireflective coating, these polymer coatings can effectively reduce or eliminate substrate reflection, swing effect and other problems caused by thin film interference. Our progress in this study has led us to the development of AZ(R) EXP HERB(TM) B.A.R.C. for 365nm exposure and the commercialization of AZ(R) EXP KrF 17B 80 B.A.R.C. for 248nm exposure. This paper will focus on development and process modification of these novel materials.