We have developed a low-cost wafer-level three-dimensional (3D) integration technology compatible with 300-mm wafers by using hybrid wafer bonding. This technology includes wafer-to-wafer (W2W) stacking technology with a copper/polymer hybrid wafer bonding and through-silicon via (TSV) reveal process. Bonding of a copper/polymer hybrid wafer achieved good copper-to-copper bonding as well as good polymer-to-polymer bonding without producing any large bonding voids. The misalignment between 300-mm bonding wafers was less than 0.57 μm. Via-middle TSVs (8 μm in diameter and 25 μm in length) were revealed by back grinding (BG) and chemical mechanical polishing (CMP). The electrical connectivity of a three-stacked wafer fabricated by hybrid wafer bonding was confirmed. These results indicate the effectiveness of the proposed 3D integration technology.
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