Direct gold and copper wires bonding on copper
| Autor: | Hong Meng Ho, Petar Ratchev, Serguei Stoukatch, Wai Lam, Charles J. Vath, Eric Beyne |
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| Rok vydání: | 2003 |
| Předmět: |
Wire bonding
Materials science Plasma cleaning Metallurgy chemistry.chemical_element Temperature cycling engineering.material Condensed Matter Physics Copper Atomic and Molecular Physics and Optics Surfaces Coatings and Films Electronic Optical and Magnetic Materials Metal Coating chemistry visual_art engineering visual_art.visual_art_medium Copper plating Wafer dicing Electrical and Electronic Engineering Safety Risk Reliability and Quality |
| Zdroj: | Microelectronics Reliability. 43:913-923 |
| ISSN: | 0026-2714 |
| DOI: | 10.1016/s0026-2714(03)00074-x |
| Popis: | The key to bonding to copper die is to ensure bond pad cleanliness and minimum oxidation during wire bonding process. This has been achieved by applying a organic coating layer to protect the copper bond pad from oxidation. During the wire bonding process, the organic coating layer is removed and a metal to metal weld is formed. This organic layer is a self-assembled monolayer. Both gold and copper wires have been wire-bonded successfully to the copper die even without prior plasma cleaning. The ball diameter for both wires are 60 μm on a 100 μm fine pitch bond pad. The effectiveness of the protection of the organic coating layer starts from the wafer dicing process up to the wire bonding process and is able to protect the bond pad for an extended period after the first round of wire bond process. In this study, oxidization of copper bond pad at different packaging processing stages, dicing and die attach curing, have been explored. The ball shear strength for both gold and copper ball bonds achieved are 5 and 6 g/mil2 respectively. When subjected to high temperature storage test at 150 °C, the ball bonds formed by both gold and copper wire bond on the organic coated copper bondpad are thermally stable in ball shear strength up to a period of 1440 h. The encapsulated daisy chain test vehicle with both gold and copper wires bonding have passed 1000 cycles of thermal cycling test (−65 to 150 °C). It has been demonstrated that orientation imaging microscopy technique is able to detect early levels of oxidation on the copper bond pad. This is extremely important in characterization of the bondability of the copper bond pad surface. |
| Databáze: | OpenAIRE |
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