Semi E43

SEMI E43 defines Electrostatic Measurements on Objects and Surfaces, the standard test method for quantifying static electrical charge on wafers, carriers, and equipment surfaces — voltage potential, decay rate, and charge polarity — so a fab can verify that its static-control measures are actually working rather than assuming they are because an ESD mat or ionizer was installed. Static charge accumulates on nearly every surface inside a fab through ordinary friction and separation events — a wafer sliding out of a carrier, a robot end-effector releasing a substrate — and without a standardized way to measure the resulting charge, there's no way to confirm whether a tool's static-control hardware is adequately dissipating it or merely present without actually working.

Static charge accumulates during normal handling
Friction/separation events: carrier unload, robot release
SEMI E43 electrostatic measurementQuantified, not assumed from installed hardware alone
Voltage potential and polarity measured
Defined probe distance and measurement conditions
Decay rate measured over time
How fast the charge actually dissipates
Static-control effectiveness verified or flagged
Confirms ionizers/grounding are actually working

E43's decay-rate measurement is often the more operationally important of the two numbers: a surface might show an acceptable peak voltage reading immediately after a charging event but take far longer than expected to actually dissipate that charge, meaning wafers handled during the slow-decay window are still exposed to a static-discharge risk even though the hardware is nominally functioning — a risk a simple pass/fail voltage check at one instant in time would completely miss. This matters directly for gate-oxide integrity and particle attraction: a charged wafer surface both risks electrostatic discharge damage to sensitive device structures and actively attracts particles electrostatically, which is why E43's quantified, repeatable measurement method exists — to give a fab a verifiable number for static-control performance instead of treating ESD mitigation as a checkbox satisfied by equipment installation alone.

SEMI E43 — Voltage Plus Decay Rate a single voltage reading alone misses the slow-decay risk Charge (V) Fast decay — compliant Slow decay — same peak voltage, hidden risk a one-time peak-voltage check cannot distinguish these two curves E43 requires the decay measurement to tell them apart

E43's static-charge measurement discipline connects directly to the contamination picture SEMI E14 and E44 cover: a charged surface doesn't just risk electrostatic discharge damage, it actively attracts the particles E14 measures a tool contributing and the particles E44's minienvironment acceptance testing is meant to keep away from the wafer in the first place.

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