Highly Robust Ti Adhesion Layer during Terminal Reaction in Micro-Bumps
Chen-Wei Kao1, Po-Yu Kung1, Chih-Chia Chang1
1Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan.
Materials (Basel, Switzerland)
|June 24, 2022
Summary
Titanium (Ti) adhesion layers show superior attachment with copper-tin intermetallic compounds (IMCs) in micro-bumps compared to chromium (Cr). Aging revealed void formation, but adhesion and strength remained unaffected, ensuring reliability.
Area of Science:
- Materials Science
- Surface Engineering
- Reliability Engineering
Background:
- Miniaturized electronics utilize micro-bumps, forming intermetallic compounds (IMCs) that enhance wetting.
- Direct contact between IMCs and adhesion layers raises reliability concerns.
Purpose of the Study:
- Investigate the terminal reaction between a titanium (Ti) adhesion layer and copper-tin (Cu-Sn) IMCs.
- Assess the impact of aging on micro-bump reliability and adhesion.
Main Methods:
- Micro-bumps with Ti adhesion layers were aged at 200 °C.
- The resulting intermetallic structures and their adhesion were analyzed.
- Void formation and its effect on bump strength were examined.
Main Results:
- All micro-bumps formed intermetallic structures with strong attachment to the Ti adhesion layer after aging.
- Void formation occurred due to differential diffusion rates of Cu and Sn but did not compromise adhesion or strength.
- Titanium demonstrated superior adhesion of IMCs compared to previously studied chromium systems.
Conclusions:
- The Ti adhesion layer offers enhanced reliability for Cu-Sn IMCs in micro-bumps.
- Titanium outperforms chromium in preventing spalling and maintaining adhesion under thermal stress.
- The study highlights Ti as a promising adhesion material for advanced electronic packaging.
