is the process of
validating (or invalidating) the
failure of the sample. The best way to verify a
failure is to electrically test the samples using the automatic test
equipment (ATE) used during production testing. The advantages of
using the ATE to verify the failure are: 1) the validation is
correlated with production standards making it more 'official'; and 2) the
ATE can give a datalog of results for each parameter, identifying the
specific failure for the analyst.
If ATE-generated datalog results are
available, their careful analysis prior to the failure analysis proper
will make a big difference in the efficiency of the FA process. As
early as datalog analysis, the analyst should be
already the possible failure mechanisms and attributes affecting the
sample, based on the
test blocks failed by the
verification is usually associated with
In fact, failure verification and characterization are sometimes
indistinguishable, especially if ATE testing of the sample is not
and current-voltage (I/V)
are very good techniques for complementing ATE testing for failure
verification and characterization.
is the process of characterizing the failure mode of the sample using
various bench equipment for
exciting the device and
its responses. Since different test parameters require different
test conditions, the analyst needs to revise the bench test set-up every
time a new test parameter needs to be characterized. As such,
failure verification may entail the use of
set-ups before the nature of device failure is fully understood.
Equipment required for effective
failure verification include various power supplies, multimeters,
frequency counters, oscilloscopes, curve tracers, break-out boxes, and the
like. Sometimes it is also necessary to build a circuit that
the application of the customer where the failure was observed. The idea is to be able to
observe the failure of the sample inside the FA lab without an ATE.
1. Typical bench test equipment for failure verification: (left to
right) power supply, multimeter, frequency counter, oscilloscope
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is the process of analyzing the current-voltage characteristics of an
electrical path using an equipment known as a
curve tracer. It can identify electrical failures that exhibit abnormal
voltage-current relationships between pins.
Curve tracing can also
be done on an electrical path inside the
circuitry itself, where the
nodes defining the electrical path are not connected to any external pins. Microprobing is employed to achieve
electrical contact with the selected nodes, with the probe needles also
attached to the curve tracer.
analysis proper should only be pursued if the analyst is convinced that
the reported failure is
Otherwise, the analyst should promptly inform the FA requestor that the
failure is invalid, and that full FA will not be performed. In such
a case, the analyst should always have
data to show
that the sample is indeed electrically good.
FA Techniques; Curve Tracing;
Equipment; Basic FA
Package Failures; Die
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