File name On-Wafer Parametric Measurement 4-On-Wafer_Parametric_Measurement c20130117 .pdf
This PDF is an excerpt from Chapter 4
of the Parametric Measurement Handbook.
Chapter 4: On-Wafer Parametric Measurement
"One must learn by doing the thing; for though you think you know it, you have
no certainty until you try." -- Sophocles
The vast majority of parametric measurements are performed on-wafer.
Obviously, this implies that you need some sort of a wafer prober to make these
measurements. What is often missed by many engineers performing on-wafer
parametric measurements are the profound effects that various factors such as
the wafer chuck, cables, wafer probes and switching matrix (if used) can have
upon their measurement results.
Fully automatic versus analytical wafer probers
Fully automatic wafer probers are designed to be used in production environ-
ments in conjunction with either parametric or functional test equipment. Fully
automatic wafer probers can test an entire cassette or FOUP (front-opening
unified pod) of wafers at a time, and they have the ability to automatically load
and align a wafer for testing. Fully automatic wafer probers are virtually always
used with some sort of a probe card and switching matrix. Due to their size,
cost, and complexity, fully automatic wafer probers are used almost exclusively
in production test environments with high-volume production testers. Since this
handbook is primarily focused on parametric test instruments, we will not spend
any additional space discussing them.
Analytical wafer probers are designed to be used in laboratory environments,
and they come in both manual and semi-automatic versions. Manual wafer
probers do not possess any electrical motors to automate any part of the wafer
alignment and stepping process, but must instead (as their name implies) be
manually adjusted each time that you want to move to a new location on the
wafer. In contrast, most semi-automatic wafer probers possess the capability to
automatically align an individual wafer; however, they typically do not support
any sort of autom