PREVENTION OF WARPING DURING HANDLING OF CHIP-ON-WAFER

摘要

To reduce the risk of reduction in yield due to breakage of a thin wafer or a thin chip having through silicon vias (TSVs) formed therein in a chip bonding process, and to prevent warping during handling of a chip-on-wafer (CoW). Chips are bonded to a wafer having TSVs formed therein and sealed before the wafer is thinned. Subsequently, the CoW is subjected to a process of thinning the TSV wafer, a back-surface treatment, and a process of cutting the wafer into small pieces by dicing. Although thin wafers and thin chips having TSVs formed therein are difficult to handle since the chips are bonded to the wafer before thinning and the wafer is thinned and cut into small pieces while mechanical strength thereof is increased by fixing a support to the wafer, the yield of three-dimensional stacked devices can be increased.

主权项

1. A method for preventing warping of a through silicon via (TSV) wafer before thinning in a process of handling the TSV wafer before thinning, the method comprising the steps of:
arranging a plurality of chips so that the chips correspond to TSVs; fixing the plurality of chips to the TSV wafer before thinning with a plurality of solder bumps to produce fixed chips; sealing a space between each chip and the TSV wafer with an underfill material to produce sealed chips; fixing a support so that the support covers the fixed and sealed chips; scraping a surface to which the TSVs do not extend while the support is fixed until the TSVs appear and are in a completely penetrating state; and dicing the TSV wafer before thinning along a region where the chips are not arranged.