A flexible nanobrush pad for the chemical mechanical planarization of Cu/ultra-low-к materials

Abstract

A new idea of polishing pad called flexible nanobrush pad (FNP) has been proposed for the low down pressure chemical mechanical planarization (CMP) process of Cu/ultra-low-к materials. The FNP was designed with a surface layer of flexible brush-like nanofibers which can ‘actively’ carry nanoscale abrasives in slurry independent of the down pressure. Better planarization performances including high material removal rate, good planarization, good polishing uniformity, and low defectivity are expected in the CMP process under the low down pressure with such kind of pad. The FNP can be made by template-assisted replication or template-based synthesis methods, which will be driven by the development of the preparation technologies for ordered nanostructure arrays. The present work would potentially provide a new solution for the Cu/ultra-low-к CMP process.

Mechanical Properties and Interface Characteristics of Nanoporous Low-kMaterials

“…Nevertheless, decreasing k value usually results in the concomitant reduction in the mechanical strength of the low- k materials. The elastic modulus of the low- k material is typically several gigapascals, which is much lower than that of SiO 2 (70–80 GPa). , Because of their poor mechanical strength, integrating low- k materials successfully into the ICs is extremely difficult, especially with regard to the device packaging and chemical mechanical polishing (CMP) process. − Delamination and cracks of low- k films could be induced during CMP due to the large difference in the mechanical strengths of different layers and lead to decreased reliability and degraded performance of IC chips. The poor ability to withstand the thermal and mechanical stresses, as well as the weak adhesion between the low- k material and its neighboring structure, has become the major roadblock in the effective applications of low- k materials …”