Microstructural stability enhancement and mechanical reinforcement of TLP-bonded Cu/Sn-3.5Ag/Cu microbumps under multiple reflow cycles through Zn Alloying and Ni substrate integration

IF 3.8 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum Pub Date : 2024-11-23 DOI:10.1016/j.vacuum.2024.113855

Yin-Ku Lee, Yun-Chen Chan, Zih-Yu Wu, Su-Yueh Tsai, Shou-Yi Chang, Jenq-Gong Duh

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引用次数: 0

Abstract

The transient liquid phase (TLP) bonding process is effective for constructing stacked structures in advanced packaging, as it allows for multiple reflow cycles without remelting. However, the various reflows can cause phase transformations, leading to internal stress-induced voids. Thus, the stability of IMC phases is particularly challenged in 3D stacking structures. Common configurations include Cu/Sn/Cu and Cu/Ni/Sn/Cu. Although Ni improves the stability of the Cu₆Sn₅ phase, phase transformation to Cu₃Sn can still occur, compromising reliability. This study investigates microstructure stability by doping Zn into the Cu/Sn-3.5Ag/Ni system across five reflow cycles. Results demonstrate that Cu-15Zn/Sn-3.5Ag/Ni microbumps reduce void formation and ensuring the phase stability of the (Cu,Ni)₆(Sn,Zn)₅ to maintain the microstructure stability. The Zn addition inhibits the Cu₃Sn layer, while optimizing grain size and orientation of (Cu,Ni)₆(Sn,Zn)₅. (Cu,Ni)₆(Sn,Zn)₅ also exhibits increased hardness and reduced modulus (E_r). These findings provide critical insights for designing sub-10-μm scale TLP-bonded microbumps in advanced packaging.

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通过锌合金化和镍基底集成，在多次回流焊循环下提高 TLP 焊接铜/锰-3.5Ag/铜微凸块的微结构稳定性并增强其机械性能

瞬态液相（TLP）键合工艺可在高级封装中有效地构建叠层结构，因为它允许多次回流焊循环而无需重新熔化。然而，各种回流可能会引起相变，导致内部应力引起的空洞。因此，在三维堆叠结构中，IMC 相的稳定性尤其面临挑战。常见的结构包括 Cu/Sn/Cu 和 Cu/Ni/Sn/Cu。虽然镍提高了 Cu6Sn5 相的稳定性，但仍可能发生向 Cu3Sn 的相变，从而影响可靠性。本研究通过在 Cu/Sn-3.5Ag/Ni 系统中掺入 Zn，在五个回流焊周期中研究微观结构的稳定性。结果表明，Cu-15Zn/Sn-3.5Ag/Ni 微凸块减少了空洞的形成，确保了 (Cu,Ni)6(Sn,Zn)5 的相稳定性，从而保持了微观结构的稳定性。锌的添加抑制了 Cu3Sn 层，同时优化了（Cu,Ni）6（Sn,Zn）5 的晶粒大小和取向。这些发现为在先进封装中设计 10 微米以下尺度的 TLP 粘合微凸块提供了重要启示。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Vacuum 工程技术-材料科学：综合

CiteScore

6.80

自引率

17.50%

发文量

审稿时长

34 days

期刊介绍： Vacuum is an international rapid publications journal with a focus on short communication. All papers are peer-reviewed, with the review process for short communication geared towards very fast turnaround times. The journal also published full research papers, thematic issues and selected papers from leading conferences. A report in Vacuum should represent a major advance in an area that involves a controlled environment at pressures of one atmosphere or below. The scope of the journal includes: 1. Vacuum; original developments in vacuum pumping and instrumentation, vacuum measurement, vacuum gas dynamics, gas-surface interactions, surface treatment for UHV applications and low outgassing, vacuum melting, sintering, and vacuum metrology. Technology and solutions for large-scale facilities (e.g., particle accelerators and fusion devices). New instrumentation ( e.g., detectors and electron microscopes). 2. Plasma science; advances in PVD, CVD, plasma-assisted CVD, ion sources, deposition processes and analysis. 3. Surface science; surface engineering, surface chemistry, surface analysis, crystal growth, ion-surface interactions and etching, nanometer-scale processing, surface modification. 4. Materials science; novel functional or structural materials. Metals, ceramics, and polymers. Experiments, simulations, and modelling for understanding structure-property relationships. Thin films and coatings. Nanostructures and ion implantation.