Advances In Au/Sn Target Materials By Rod Martinez, Marketing Manager - PVD Products During the past several years, Williams Advanced Materials (WAM) has provided consistent and homogeneous 80Au20Sn targets and evaporation material. The materials are used for low film resistivity backside wafer metallization and more importantly, for backside solder thin films used in discrete elements for wafer support (wafer chip soldering).
Recent developments in the fiber-optic component market have given WAM the opportunity to expand and support the shift from pick and place AuSn preforms to thin films already deposited on the substrate. This new emerging alternative on opto-electronic devices allows complex solder pad geometry as well as thinner coatings.
Williams AuSn targets and evaporation material offer the highest level of homogenous compositional structure possible. Small metallurgical grain size and a homogeneous structure are key PVD characteristics for optimal process yields and film performance (i.e. deposition rate and film uniformity). Due to the brittle nature of AuSn alloys, state-of-the-art casting technology have been designed for optimal grain size and the elimination of material segregation.
WAM has also developed other AuSn alloys to compensate for preferential sputtering and/or evaporation. "Off" eutectic alloy compositions have been determined and tested to adjust to certain processes where Au "heavy" films were produced.
The feedback from our customers has been extremely positive. Our processes continue to have the highest reproduction rate at the lowest cost possible. Williams’ in-house Refining and Recycling capabilities allow our customers to recover their used and spent material as fast as possible (average of 5 days) to minimize their material inventory to meet current and future production demands. With a commitment to continuous process development and material management, Williams AuSn material and refining services continue to improve the manufacturing of discrete elements in emerging IC technologies.
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