SEMI MF81 - Test Method for Measuring Radial Resistivity Variation on Silicon Wafers -

Abstract

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)

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