Super planarizing material for trench and via arrays

As device design scales and becomes more complex, fine control of patterning and transfer steps is integral. Planarization of deep trenches and via arrays has always been a challenge. Aspect ratios continue to increase while critical dimensions shrink, and typical trench fill schemes are no longer able to meet the fill and planarization requirements. Traditional design of spin-on carbon (SOC) materials for planarization normally incorporates low viscosity and high crosslink temperature to allow for the material to thermally flow. However, thermal flow is limited by the force needed to drive this flow, the crosslinking reaction, and the surface tension. This is especially important in deep trenches and vias, where there is a need to move a large amount material. A new type of planarizing material is presented that uses Marangoni effect to pull material to the dense feature area. This force is much stronger than gravity during thermal reflow, and it can be controlled by careful selection of material and process. Based on the structure of substrate, it is possible to adjust the intensity of force and balance with viscosity and flow time to achieve perfect planarization. The technology is not wavelength-specific and could be used in lithography applications from i-line to EUV. The design can also be incorporated into a wide range of SOC platforms for both low- and high-temperature applications.