February 18, 2014

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Ion Implantation – Cluster architecture & Increased Throughput

This is a brief overview of exiting variants of ion implantation soft wares used in a typical FAB environment and advantages of introducing cluster architecture for them. This is done by drawing a parallel with existing cluster tools that are used in the other semiconductor areas namely wafer inspection methodology.

Cluster is an emerging architecture in semiconductor industry that is widely used in the yield management tools like wafer inspection and measurement software.  The whole idea is to enhance the throughput of these softwares and cut down the underlying operating costs of the otherwise non-cluster tools.

Cluster tools as the name implies is the assimilation of either identical or non-identical control software tools in to a single operating platform. The single operating platform comprises basically

  • a robot to transfer the wafer for inspection,
  • set of load ports and carriers that has the wafers ready for inspection and
  • multiple stages where the wafer will traverse through, to undergo various inspection mechanisms in a single job cycle.

Ideally in non-cluster environment, there would be only one stage pertaining to the wafer inspection software and a single robot would serve only one wafer at a time, to the only stage of the tool for inspection, and returns the wafer back to load port.  It is time consuming, as the wafer that is returned to the carrier has to be again fed through other inspection tool software and the cycle is repeated. Cluster architecture addresses this problem by sequentially handling of wafer across multiple control software stages and finally returns the wafer to the carrier.

While ion implantation tool is very different from wafer inspection tools, the idea of sequential processing of multiple implantations in one go for a wafer, shall be a nice to have facility. That is, processing implantations across multiple ion implanters and finally returning the wafer to the carrier.  Because, this will improve the wafer processing time and ultimately improve the productivity of the tool in terms of yield i.e. more implantations achieved in shorter span of time.

Though theoretically it sounds good, the real challenge would be to assimilate all the hardware of different variants of the implantation tools under one common hood and enable them to co-exist and operate consecutively. Under current setup we would be having a set of robots and a quad load ports for each variant of the implantation software, thus totaling to six robots and twelve load ports.  Whereas in cluster environment, the same throughput can be achieved by merely having two robots and a quad load port serve multiple implantation softwares under one common platform. The hardware cost and the maintenance cost is cut by adopting cluster environment. However the real challenge is to explore the feasibility of hardware adaptability to cluster setup and the cost incurred to invest in such an idea.Read more about the Semiconductor industry here

References

  1. http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=5474977&url=http://ieeexplore.ieee.org/iel5/5470287/5474884/05474977.pdf%3Farnumber%3D5474977