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The effects of thermocompression bonding on Si/SiO2 multilayer thin-film based critical dimension structures

The development of semiconductor industry has made nanometrology more and more important, of which Si/SiO2 multilayer thin-film based critical dimension structures is one of the potential certified reference materials to calibrate measurement instruments. However, in the fabrication process, the quality of the bonding step mainly influences the performance of final structures. In this study, we applied thermocompression bonding method to eliminate the side effect, such as the contamination of adhesive layer and the influence of the adhesive layer on AFM probes caused by the traditional adhesive bonding. Further, thermocompression bonding realized simultaneous observation on both left and right structures in different wafers. On this basis, we also discussed the influence of the size of the silicon wafer, bonding temperature and pressure on bonding performance. The images show that small size is more conducive to improve bonding quality. Besides, the AFM measurement results indicate that Si/SiO2 multilayer thin-film can remain undeformed under higher temperature and pressure (200°C-300°C, 0.6MPa-1.0MPa). This method provides support for Si/SiO2 multilayer thin-film based critical dimension to become high quality certified reference material.