Self-Assembly of Chip-Size Components with Cavity Structures: High-Precision Alignment and Direct Bonding without Thermal Compression for Hetero Integration

Takafumi Fukushima, Takayuki Konno, Eiji Iwata, Risato Kobayashi, Toshiya Kojima, Mariappan Murugesan, Ji Chel Bea, Kang Wook Lee, Tetsu Tanaka, Mitsumasa Koyanagi

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)

Abstract

New surface mounting and packaging technologies, using self-assembly with chips having cavity structures, were investigated for three-dimensional (3D) and hetero integration of complementary metal-oxide semiconductors (CMOS) and microelectromechanical systems (MEMS). By the surface tension of small droplets of 0.5 wt% hydrogen fluoride (HF) aqueous solution, the cavity chips, with a side length of 3mm, were precisely aligned to hydrophilic bonding regions on the surface of plateaus formed on Si substrates. The plateaus have micro-channels to readily evaporate and fully remove the liquid from the cavities. The average alignment accuracy of the chips with a 1mm squarecavity was found to be 0.4μm. The alignment accuracy depends, not only on the area of the bonding regions on the substrates and the length of chip periphery without the widths of channels in the plateaus, but also the area wetted by the liquid on the bonding regions. The precisely aligned chips were then directly bonded to the substrates at room temperature without thermal compression, resulting in a high shear bonding strength of more than 10 MPa.

Original languageEnglish
Pages (from-to)49-68
Number of pages20
JournalMicromachines
Volume2
Issue number1
DOIs
Publication statusPublished - 2011

Keywords

  • Cavity chip
  • Direct bonding
  • Hetero integration
  • Liquid
  • Room-temperature bonding
  • Self-assembly
  • Surface tension

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Mechanical Engineering
  • Electrical and Electronic Engineering

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