The Nimbus
The Nimbus is the workhorse of the PVD world, with more than 5 million wafers/year processed at more than 25 customer sites worldwide in every wafer-level packaging PVD application.
The Nimbus combines many of the features and capabilities of cluster tools with the low cost and simplicity of in-line systems. The Nimbus architecture is more efficient than cluster tools for UBM applications where multiple metals are deposited. In a cluster tool, a single process chamber (for example, to deposit a titanium adhesion layer) will remain idle most of the time. In the Nimbus, all wafers have the adhesion layer deposited in one step with an immediate change in targets for the next process step. In this architecture, the deposition chambers are processing nearly full time. High throughput, small footprint, and remarkable flexibility make the Nimbus the ideal tool for many advanced packaging applications.
The Nimbus places wafers on a tray at atmospheric pressure, with all subsequent vacuum process steps carried out with no further wafer movement. This architecture permits the use of any end effectors, including Bernoulli, for wafer transfers. The Nimbus' wafer handling is superior to that of cluster tools, as the Nimbus does not require any wafer transfers in vacuum.
The Nimbus has been demonstrated to perform superior etch applications to cluster tools. The Nimbus leaves less oxide regrowth between etch and deposition, resulting from the wafer remaining at high vacuum as it moves from etch to deposition, rather than passing through a central handler. This lack of oxide regrowth is particularly important in applications in analog devices.
The Nimbus is capable of depositing all materials commonly seen in cluster tools; however, in addition, the Nimbus geometry and scanning feature of the deposition chamber enables the Nimbus to deposit pure nickel with 350 kWh in target life. This requirement is becoming increasingly important in many UBM structures.
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