Chemistry working for lithography: the Marangoni-effect-based single layer for enhanced planarization

摘要

In the field of semiconductor manufacturing, there is still a continuous search for techniques to improve the Critical Dimension Uniformity (CDU) across the wafer. CDU improvement and general defectiveness reduction increase the industrial yield and guarantee high reliability standards. In the KrF Dual-Damascene module integration, at a lithographic level, deep trench planarization is mandatory to minimize interference patterns of the photoresist known as the swing curve effect. Swing curve models explain why small changes in the film thickness of the photosensitive material can create wide critical dimensions changes. Different approaches have been developed to improve the CDU, like the etch-back approach and partial via filling. Within the plethora of materials studied to improve the performances, the Marangoni-effect based underlayers are now showing their potential. In the past, an extensive testing of a double-layer solution comprising one Marangoni-effect-based material and one standard underlayer has been carried out with success. Despite this, double-layer spinning brings drawbacks at manufacturing level, increasing the cost and limiting the tools' throughput. A new solution, resulting from the chemical tuning of the material exploiting the Marangoni effect has brought to the synthesis of a new single-layer planarization material, with properties similar to the previously tested double-layer approach. This advanced material opens the pathway to an alternative and cost-effective way to solve the issues typical of this module integration.