Selective Transfer of Si Thin-Film Microchips by SiO₂ Terraces on Host Chips for Fluidic Self-Assembly

• Main Authors: Yutaka Fujita, Shoji Ishihara, Yuki Nakashima, Kosuke Nishigaya, Katsuaki Tanabe
• Format: Article
• Language: English
• Published: MDPI AG 2021-02-01
• Series: Applied Mechanics
• Subjects: semiconductor; silicon; thin film; layer transfer; self-assembly; integration
• Online Access: https://www.mdpi.com/2673-3161/2/1/2

Fluidic self-assembly is a versatile on-chip integration method. In this scheme, a large number of semiconductor microchips are spontaneously deposited onto a host chip. The host chip typically comprises a Si substrate with an array of pockets at the designated microchip placement sites. In this study, we installed an SiO₂ layer on the terrace region between the pockets of the host chip, to reduce the attraction with the Si microchips. By the SiO₂-topped terrace scheme, we demonstrated a significant enhancement in the deposition selectivity of the Si microchips to the pocket sites, relative to the case of the conventional Si-only host chip. We theoretically explained the deposition selectivity enhancement in terms of the van der Waals interaction. Furthermore, our quantitative analysis implicated a potential applicability of the commonly used interlayer dielectrics, such as HfO₂, silsesquioxanes, and allyl ethers, directly as the terrace component.