Lothar Brencher

Influence of BARC filtration and materials on the reduction of spire defects

The fabrication of semiconductor devices can be complicated by various defectivity issues with respect to fabrication process steps, their interactions, the used materials and tool settings. In this paper we will focus on a defect type, called spire or cone defect. This conducting defect type is very common in the shallow trench isolation (STI) process. The presence of a single defect can be responsible for a device breakdown or reliability problems, which will result in a serious impact on the competitive edge for a product qualification. Spire defects, which can only be detected after etch, are observed on all our technology nodes using 248nm or 193nm exposure techniques. Bottom Anti-Reflection Coatings (BARC) impurities are considered to be the main root cause for the formation of spire defects. Therefore we focused our efforts on chemical filtration of the BARC material and related solvents, the usage of different BARC materials and the influence of the subsequent etch steps in order to reduce or overcome the spire defect problem. In this paper we will discuss the effectiveness of different filter materials, pore sizes and different BARC materials (organic and dielectric BARC) with respect to defect analysis and lithographic performance.