New precision wafer bonding technologies for 3DIC

A new precision wafer-to-wafer (W2W) bonding system for three-dimensional integrated circuits (3DICs) fabrication including a new precision alignment methodology and a unique thermocompression bonding procedure is proposed. Experimental results show that the alignment capability is 100 nm or better, and permanent bonding accuracy of 260 nm (|mean| + 3σ) in 300 mm Cu wafer bonding. An analysis of overlay error components is useful for identifying the causes of the error and improving the tool conditions. These capabilities are key enablers for the future of cost-effective 3DIC manufacturing.