Evaluation of alignment accuracy on chip-to-wafer self-assembly and mechanism on the direct chip bonding at room temperature

Chip-to-wafer bonding is a promising technology for 3D integration due to high production yield using known good dies (KGDs). However, conventional chip-to-wafer 3D integration lowers production throughput because pick-and-place chip assembly is employed. To overcome the problem, we proposed a new chip-to-wafer 3D integration using self-assembly by which many KGDs can be simultaneously, rapidly, and precisely aligned and tightly bonded on wafers. The driving force is liquid surface tension. Here, we used an aqueous solution including dilute HF. In this paper, we discuss the dependence of alignment accuracy on several parameters in self-assembly conditions. In addition, we describe mechanism on HF-assisted direct chip bonding to wafers without thermal compression.