Mechanism of carbon particle-induced latent leakage between metal lines. (September 2019)

• Record Type: Journal Article
• Authors: Qin, Wentao; Deal, Paul; Steinwall, Jim; Kabadi, Raj; Chang, George; Ruiz, Bladimiro; Barrientos, Denise
• Is Part Of: Microelectronics and reliability. Volume 100/101(2019)
• Publication Date: 2019-09
• Subjects: Carbon -- Particle -- Leakage -- Shorting -- Latent -- Pyrolysis -- Pi bond -- sp2 -- sp3; Electronic apparatus and appliances -- Reliability -- Periodicals; Miniature electronic equipment -- Periodicals; Appareils électroniques -- Fiabilité -- Périodiques; Équipement électronique miniaturisé -- Périodiques; Electronic apparatus and appliances -- Reliability; Miniature electronic equipment; Periodicals; 621.3815
• DOI: 10.1016/j.microrel.2019.06.087
• Languages: English
• ISSNs: 0026-2714

Abstract

Abstract: Leakage between metal lines is a common and frequently-encountered problem for microelectronic devices which can usually be detected electrically at probe or final test. However, a latent issue of leakage between metal lines escapes such test screening and causes failure at reliability test or even in customer application. Such an issue was discovered at reliability test. An amorphous carbon particle between adjacent metal lines was found. Electron energy loss spectroscopy (EELS) analysis revealed a significant fraction of sp2 bonding in the particle. The particle received thermal energy from wafer processing and the reliability test, which caused pyrolysis of the particle, and in turn densification, carbon enrichment, and likely graphitization of the particle catalyzed by the metals. The resultant conductivity increase led to the latent leakage between the metal lines. Preventive measures to counter the issue are stated. Highlights: A particle of photoresist residue, consisting of amorphous carbon, caused latent leakage between the metal lines. Thermal energy from the ensuing wafer processing and reliability test had induced pyrolysis of the particle. The carbon particle contained a significant fraction of sp2 bonding per EELS analysis. The π electrons in the sp2 orbitals are delocalized and become charge carriers in electric fields. The conductivity of amorphous carbon increases with its sp2 content. This was how the particle caused the latent leakage. Pyrolyzed photoresists have been used as conductive materials such as electrodes for supercapacitors and batteries. The fact aligns well with our observation and interpretation of the latent leakage.