Optimization of bottom antireflective coating materials for dual damascene process

Abstract

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 O.3O-O.5Otm and O.l8-O.25m with aspect ratios of3 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 365nm 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® EXP HERBTM B.A.R.C. for 365nm exposure and the commercialization ofAZ® EXP KrF 17B 80 B.A.R.C. for 248nm exposure. This paper will focus on development and process modification ofthese novel materials.

Structure effects of silicon-containing antireflection coatings

“…In addition, some substrate surfaces have deposited low E materials that release components detrimental to the photoresist, resulting in a pattern “footing” or “scumming.” 5 Therefore, bottom antireflective coatings (BARCs) have been widely used to eliminate these effects 4 – 7 BARC refers to a layer between photoresist and substrate that can effectively eliminate the interference standing wave caused by reflected light. The coating reduces the impact of differences in the substrate geometry while absorbing reflected light, eliminating standing waves, and preventing the adverse effects of the substrate on the photoresist.…”