Tungsten cap metallization for 0.5 μm via fill technology

• Published in: Journal of the Electrochemical Society 1995-11, Vol.142 (11), p.3893-3896
• Main Authors: WOO, M, FIORDALICE, B, LIN, J.-H, KOLAR, D
• Format: Article
• Language: English
• Subjects: Applied sciences; Electronics; Exact sciences and technology; Microelectronic fabrication (materials and surfaces technology); Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/1.2048430

A metallization stack is fabricated using a W cap layer on top of the aluminum interconnect. Utilizing this stack significantly reduces the possibility and process-induced defectivity problems: formation of via veils, metal extrusions, and breakdown in the via glue layer. Conventional via etching is shown to stop successfully on the W capping layer without forming via veils or resputtering the underlying Al substrate. Experimentally, the W cap is shown to provide superior resistance to metal extrusion phenomena which are associated with high temperature chemical vapor deposition W processing. Integrated with W via fill technology and using only a sputtered titanium nitride via glue layer, acceptable via resistance is demonstrated. Electrical performance shows the W-capped via resistance to be approx0.60 Omega /via higher than conventional metallization scheme for a 0.65x0.65 mu m size via. Metal snake and comb tests show no difference between the standard metallization stack and the W cap structure indicating differences in patterning defectivity to the statistically insignificant. Normalized static random access memory (SRAM) yield is shown to be equivalent between the two splits.