Hidehiro Maeda

High-precision wafer-level Cu-Cu bonding for 3DICs

A high-precision Cu-Cu bonding system for three-dimensional integrated circuits (3DICs) fabrication adopting a new precision alignment methodology is proposed. A new pressure profile control system is applied in the thermocompression bonding process. Experimental results show that the alignment capability is 250 nm or better, with similar overlay accuracy (|average| + 3σ) for permanent bonding. These developments are expected to contribute to the fabrication of future 3DICs.

New precision alignment methodology for CMOS wafer bonding

A new precision alignment methodology suitable for distorted CMOS wafer bonding is proposed. Using multiaxis-interferometer and load-cell measurements with in situ fine stage-position adjustment combined with newly designed wafer holders, two wafers are flattened and aligned precisely. The alignment capability is 250 nm or better without any damage to low-k materials, making the methodology suitable for future 3D integration.

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.

Precision wafer bonding process for future cost-effective 3DICs

A high-precision wafer-to-wafer (W2W) bonding system for three-dimensional integrated circuits (3DICs) fabrication adopting a new precision alignment methodology is proposed. In studying W2W device yield, the authors split the stacking W2W yield formula to better understand the systematic versus random components, and propose that miniaturization yield and wafer stacking yield should be considered separately. Experimental results show that the W2W alignment capability is 250 nm or better, with similar overlay accuracy (|mean| + 3σ) for high-throughput Cu-Cu permanent bonding. These capabilities are key enablers for the future of cost-effective 3DIC manufacturing.

High precision alignment process for future 3D wafer bonding

A new precision alignment process suitable for bonding distorted CMOS wafers is proposed. This process includes the following critical procedures: (A) correction of distorted wafers, (B) enhanced global alignment (EGA) for wafer-to-wafer (W2W) bonding, (C) contact between wafers with high alignment accuracy, and (D) clamping to maintain pre-bonding accuracy. The alignment capability was measured by our newly developed IR metrology tool. We obtained an alignment capability of better than 100 nm both theoretically and experimentally.

High-Precision Wafer-Level Cu–Cu Bonding for 3-DICs

A high-precision Cu-Cu bonding system for 3-D ICs (3-DICs) fabrication adopting a new precision alignment methodology is proposed. A new pressure profile control system is applied in the thermocompression bonding process. Experimental results show that the alignment capability is 250 nm or better, with similar overlay accuracy (|average| + 3σ) for permanent bonding. These developments are expected to contribute to the fabrication of future 3-DICs.