Advanced packaging (3D and chiplets)

Which is a challenge of wafer-on-wafer (W2W) bonding, which bonds entire wafers together?

  1. ABonding alignment is impossible
  2. BBecause good and bad chips cannot be paired selectively, the yield after stacking drops to the product of the individual yields
  3. CWafers can be bonded even if their sizes differ
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Answer: B. Because good and bad chips cannot be paired selectively, the yield after stacking drops to the product of the individual yields

W2W bonding joins all chips at once and excels in throughput and alignment accuracy. But because it bonds regardless of which chips on the upper and lower wafers are good, bonding two wafers with 90% yield gives about 81% after stacking. It is therefore used for combinations of high-yield chips, such as memory cell arrays and peripheral circuits.

  • A. W2W bonds with highly accurate alignment.
  • B. Correct. Bad chips cannot be excluded from the pairing.
  • C. Wafers of the same size are bonded together.
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More Advanced packaging (3D and chiplets) questions

  1. In 2.5D packaging, what is the main advantage of using an interposer made of redistribution layers (RDL) of organic dielectric and copper wiring instead of a silicon interposer?
  2. Through the HBM3 generation, which is the data bus width per HBM stack?
  3. When a TSV wafer is thinned to tens of micrometers and processed, which technique temporarily attaches it to a support wafer (carrier) to prevent cracking and warpage?
  4. In fan-out wafer-level packaging, what is the wafer-like form called that is rebuilt by placing diced chips with spacing on a support and embedding them in resin?
  5. Which is a challenge of moving to chiplets?