Room Temperature Si–Si Direct Bonding Technique Using Velcro-Like Surfaces

Si surfaces were functionalized by anodization to create nanoneedles. Such surfaces allow Velcro-like bonding at room temperature with large bond strength for such functionalized surfaces. In addition, Velcro-like bonding has a capability of multiple bonding and debonding of the same surfaces analogous to the Velcro principle. To employ such surfaces and the bonding technique in wafer or chip bonding or in integrated circuit packaging applications, understanding the fabrication and the bonding mechanism between such surfaces is very crucial. This paper presents a simple silicon-based technology to generate Velcro-like surfaces using the anodization of Si wafer in a hydrofluoric acid-based electrolyte, and describes the bond strength between such surfaces using the van der Waals force approach. The capability of the technique and the validity of the proposed van der Waals force model are shown by comparison with the experimental results.