High-Aspect Ratio Planarization using Self-Leveling Materials

There are an increasing number of applications in the microelectronics industry that require materials that can fill and planarize high-aspect ratio topography. These applications call for the formation of a flat coating surface without the use of high bake temperatures or high-pressure processes. Potential device markets include MEMS, 3D-ICs, LEDs, semiconductors, flat panel displays and related microelectronic and optoelectronic devices. Various polymeric coating materials have been developed that have intrinsic self-leveling properties and are able to fill deep trenches and holes found on microelectronic substrates without forming voids. These new materials are able to reflow at modest baking temperatures (50–100 °C) and can fill high-aspect ratio features (10:1) by spin coating single or multiple layers of material over the topography. Several of these polymeric materials remain soluble in TMAH (and other aqueous bases), some are photosensitive, and all materials are compatible with industry-accepted solvents. Results from extended process development work on self-leveling polymeric materials will be discussed and comparisons made to industry-accepted practices.