Aluminum bond pads on semiconductor chips play an important role in IC device reliability and yield. In the paper, the vertical tension loading transferred from the capillary is clarified as the direct driving force for bond pad metal peeling. The crack on the bonding pad is identified as the root cause of the pad peeling. It is simulated by finite element method to find the effect of driving force resulting in the crack during the ultrasonic wire bonding process. It indicated that the horizontal vibration of the capillary controlled by ultrasonic power of the bonding machine was the main factors led to the crack on the bonding pad as well as its propagation into the oxide layers in chip.
The degradation of Au wire/Al bond pad has become a major bonding failure problem. It is because that the molding resin with low thermal stability (e.g. bi-phenyl epoxy resin) and the IC devices under high thermal environments were used in packaging process. For the lifetime to bond failure, the bi-phenyl epoxy molding becomes shorter than that for cresol novolac epoxy due to the corrosion reaction of Au-Al intermetallics with bromine (Br) contained in the resin compounds. It was clarified that the reactive intermetallic was Au4Al phase formed in the bond interface.
In addition, by utilizing the SEM, AES, EDS and XPS techniques, it could be carried out to reveal and identify defects underneath Al layer, and the contaminated Al bond pads could cause poor intermetallic growths led to the failed or unreliable connections from the chip to the outside world.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0706104-165951 |
| Date | 06 July 2004 |
| Creators | Ho, Ming-zhe |
| Contributors | H. Y. Ueng, Wei-zhou xu, Zhi-xiong liao, Qiu-bing chen, Ai-na hong |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0706104-165951 |
| Rights | not_available, Copyright information available at source archive |
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