Results in Physics (Dec 2021)

Effect of oxidation on electromigration in 2-µm Cu redistribution lines capped with polyimide

  • I-Hsin Tseng,
  • Po-Ning Hsu,
  • Wei-You Hsu,
  • Dinh-Phuc Tran,
  • Benson Tsu-Hung Lin,
  • Chia-Cheng Chang,
  • K.N. Tu,
  • Chih Chen

Journal volume & issue
Vol. 31
p. 105048

Abstract

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Polyimide (PI) has been adopted to protect the Cu from oxidation in the packaging industry. Electromigration (EM) of Cu redistribution layers (RDLs) capped with PI was investigated at 160 °C under 1.0 × 106 A/cm2. The results indicated that failure of fine-pitched (2-µm) is different from that of 10-µm RDLs, which is void formation. The failure of the 2-µm RDLs is mainly caused by severe oxidation during EM. To analyze the EM failure of the Cu RDLs with different pitches, the oxidation area of nanotwinned copper (nt-Cu) and regular Cu RDLs during EM was compared. We propose an oxidation equation to estimate the resistance increase of RDLs with various widths.

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