Study on ADI CD bias correlating ABC function
2015
As the technology node of semiconductor industry is being driven into
more advanced 28 nm and beyond, the critical dimension (CD) error
budget at after-development inspection (ADI) stage and its control are
more and more important and difficult (1-4). 1 nm or even 0.5 nm CD
difference is critical for process control. 0.5~1 nm drift of poly linewidth
will result in a detectable off-target drift of device performance. The
0.5~1 nm CD drift of hole or metal linewidth on the backend interconnecting
layers can potentially contribute to the bridging of metal
patterns to vias, and thereby impact yield. In this paper, we studied one
function in the scanning electron microscope (SEM) measurement, i.e.
the adjustment of brightness and contrast (ABC). We revealed how the
step of addressing focus and even the choice of addressing pattern may
bring in a systematic error into the CD measurement. This provides a
unique insight in the CD measurement and the measurement consistency
of through-pitch (TP) patterns and functional patterns.
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