Fabrication of low-elastic modulus micro bumps by controlling crystallographic orientation

2015 Fiscal Year Final Research Report

• Project/Area Number: 26630144
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Electron device/Electronic equipment
• Research Institution: Tohoku University
• Principal Investigator: Suzuki Ken 東北大学, 工学(系)研究科(研究院), 准教授 (40396461)
• Project Period (FY): 2014-04-01 – 2016-03-31
• Keywords: マイクロバンプ / 銅 / 電界めっき / 三次元実装 / 機械特性

Outline of Final Research Achievements

In this study, the fabrication method of low-elastic modulus micro Cu bumps with (100) crystallographic orientation was studied for reducing the thermal and residual stresses in three-dimensional (3D) integration of silicon microelectronic devices. Crystallographic orientation and quality of the atomic arrangement of the electroplated thin films were measured by XRD (X-ray diffraction) analysis and EBSD (Electron Back Scattering Diffraction) method. All the electroplated samples formed on the α-Ta/Cu base layer are oriented (111) preferentially. However, the ratio of (100) orientation in an electroplated Cu film was increased by applying β-Ta/Cu base layer. Young’s modulus of the film were measured by Nano-Indentation test and Young’s modulus of the film with (100) orientation decreased to 127 GPa from 145 GPa in the (111) oriented film. Therefore, the low-elastic modulus Cu micro bumps should be realized by usingβ-Ta/Cu base layer for the Cu electroplating.

Free Research Field

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