characterization, modeling, and design of esd protection circuits

Chapter 6
Conclusion
In the integrated-circuit industry, the ceaseless effort to decrease critical transistor
dimensions in each new technology guarantees that the prominence of electrostaticdischarge
will continue to grow. Devising ways to protect smaller transistors against ESD
is just as important as determining how to process and manufacture them because a
product with a high susceptibility to damage will not be widely accepted. As a result of its
gradually increasing visibility over the last two decades, the problem of ESD is now dealt
with by most IC manufacturers on several levels, from designing on-chip protection
circuits to properly grounding the furniture and equipment in a fabrication facility to
educating all personnel involved with wafer and package handling to minimize the
potential for failure. Once an IC is packaged and shipped to a customer, however, the
built-in protection circuit is the only means of defense against ESD damage. While circuit
designers have successfully created robust ESD protection for past technologies, a lack of
understanding of the mechanisms underlying ESD damage limited the amount of
transferrable knowledge from one technology to the next.
With continually decreasing technology cycles, which are now less than two years in
length, and the probable change in the prominent ESD failure mode from HBM-type
damage to CDM-type damage in deep submicron technologies, ESD circuit designers will
no longer have time to start designs from scratch or follow a trial-and-error design
approach. Characterization and design methodologies, based on an understanding of the
failure mechanisms behind ESD and models which accurately describe these mechanisms,
must be implemented so that the critical features of a protection circuit can be determined
and applied to future technologies. This chapter reviews the contributions of this thesis
toward implementing such a methodology and proposes future work to be done in the area
of ESD circuit characterization, modeling, and design.
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