Prevention of copper corrosion on post-FIB wet stained sample using UV charge-neutralization method

• Published in: Microelectronics and reliability 2020-06, Vol.109, p.113636, Article 113636
• Main Authors: Lee, Sharon, Li, Li Hong, Khoo, Ley Hong, Ang, Poh Chuan, Mo, Zhi Qiang
• Format: Article
• Language: English
• ISSN: 0026-2714; 1872-941X
• DOI: 10.1016/j.microrel.2020.113636

This paper presents the study of various charge neutralization methods to prevent copper corrosion on post-FIB wet stained sample. Conventional fast and economic wet staining on post-FIB copper processed sample can sometimes cause unwanted artifact such as copper corrosion due to build-up of charges on non-grounded, long copper interconnect structures during FIB milling. Some charge neutralization methods such as probe-pin grounding, conductive paint application and UV treatment were investigated on an ET structure. The recommended method, using UV treatment, is applied to the die area on a bulk Si wafer and on a SOI (Si-on-insulator) wafer to compare the effect of this method in preventing the copper corrosion effect. •Conventional wet delineation on post-FIB copper-structure samples can cause unwanted artifact such as copper corrosion.•This electrochemical corrosion was due to the build-up of charges on electrically floating, big, long or bulk copper structure during FIB milling.•Copper corrosion on such samples can be prevented with the application of charge neutralization method prior to wet delineation.•Some charge neutralization methods were studied. UV treatment method is recommended to prevent the copper corrosion effect.