Three-dimensional wafer stacking using Cu–Cu bonding for simultaneous formation of electrical, mechanical, and hermetic bonds
Wafer-on-wafer stacking is demonstrated successfully using bumpless Cu-Cu bonding for the simultaneous formation of electrical connection, mechanical support, and hermetic frame for 3-D IC application. The ohmic behavior of the Cu-Cu bond is verified. A daisy chain of at least 44 000 contacts at a 1...
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| Main Authors: | , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | English |
| Published: |
2013
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| Subjects: | |
| Online Access: | https://hdl.handle.net/10356/102699 http://hdl.handle.net/10220/16479 |
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| Institution: | Nanyang Technological University |
| Language: | English |
| Summary: | Wafer-on-wafer stacking is demonstrated successfully using bumpless Cu-Cu bonding for the simultaneous formation of electrical connection, mechanical support, and hermetic frame for 3-D IC application. The ohmic behavior of the Cu-Cu bond is verified. A daisy chain of at least 44 000 contacts at a 15-μm pitch is connected successfully and sustains thermal cycling. Postbonding delamination is found to be strongly affected by the wafer curvature and bond strength. The Cu-Cu hermetic seal ring shows a helium leak rate more than ten times lower than the reject limit (5 × 10-8 atm · cm/s based on MIL-STD-883E standard) without underfill. This provides a robust IC-to-IC connection density of 4.4 × 105 cm-2, suitable for future wafer-level 3-D integration. |
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