The radial resistivity variation of bulk semiconductor
material is an important materials acceptance requirement for semiconductor
device fabrication and is also used for quality control purposes.
The four-point probe method provides a test that requires
little specimen preparation and that is nondestructive in that the wafer is
left intact. The method can be applied to wafers using the
resistivity-measuring apparatus and procedures of SEMI MF84 if provisions are
made for making measurements at several sites on the wafer. Appropriate
correction factors must be applied to compensate for effects of the wafer
geometry.
Radial resistivity variations are a function of the crystal
growth process and dopant, in both characteristic shape and magnitude. Because
no single sampling plan is adequate to characterize the resistivity variations
of all crystal types or for all applications, four sampling plans are included
in this test method.
This Test Method provides procedures for the determination
of relative radial variation of resistivity of semiconductor wafers cut from
silicon single crystals grown either by the Czochralski or floating-zone
technique.
This Test Method provides procedures for using SEMI MF84
for the four-point probe measurement of radial resistivity variation.
This Test Method yields a measure of the variation in
resistivity between the center and selected outer regions of the specimen. The
amount of information obtained regarding the magnitude and form of the
variation in the intervening regions when using the four-point probe array
depends on the sampling plan chosen. The interpretation of the variations
measured as radial variations may be in error if azimuthal variations on the
wafer or axial variations along the crystal length are not negligible.
This Test Method can be applied to single crystals of
silicon in circular wafer form, the thickness of which is less than one-half of
the average probe spacing, and the diameter of which is at least 15 mm (0.6 in.).
Measurements can be made on any specimen for which reliable resistivity
measurements can be obtained. The resistivity measurement procedure of SEMI MF84
has been tested on specimens having resistivities between 0.0008 and 2000 Ω·cm
for p-type silicon and between 0.0008 and 6000 Ω·cm for n-type silicon.
Geometrical correction factors required for these measurements are included for
the case of standard wafer diameters, and are available in tabulated form for
other cases.
Referenced SEMI Standards (purchase separately)
SEMI M1 — Specification for Polished Single Crystal Silicon
Wafers
SEMI M59 — Terminology for Silicon Technology
SEMI MF84 — Test Method for Measuring Resistivity of
Silicon Slices with a Collinear Four-Probe Array
SEMI MF2074 — Guide for Measuring Diameter of Silicon and
Other Semiconductor Wafers
Revision History
SEMI MF81-1105 (Reapproved 1221)
SEMI MF81-1105 (Reapproved 0316)
SEMI MF81-1105 (Reapproved 0611)
SEMI MF81-1105 (technical revision)
SEMI MF81-01 (first SEMI publication)
