This Test Method  covers the measurement of net carrier density and net carrier density profiles in epitaxial and polished bulk silicon wafers in the range from about 4 × 1013 carriers/cm3 to about 8 × 1016 carriers/cm3 (resistivity range from about 0.1 Ω·cm to about 100 Ω·cm in n-type wafers and from about 0.24 Ω·cm to about 330 Ω·cm in p-type wafers).
 

This Test Method requires the formation of a Schottky barrier diode with a mercury probe contact to an epitaxial or polished wafer surface. Chemical treatment of the silicon surface may be required to produce a reliable Schottky barrier diode.  The surface treatment chemistries are different for n- and p-type wafers. This Test Method is sometimes considered destructive due to the possibility of contamination from the Schottky contact formed on the wafer surface; however, repetitive measurements may be made on the same test specimen.
 

This Test Method may be applied to epitaxial layers on the same or opposite conductivity type substrate. This Test Method includes descriptions of fixtures for measuring substrates with or without an insulating backseal layer.
 

The depth of the region that can be profiled depends on the doping level in the test specimen. Based on data reported by Severin2 and Grove,  Figure 1 shows the relationships between depletion depth, dopant density, and applied voltage together with the breakdown voltage of a mercury silicon contact. The test specimen can be profiled from approximately the depletion depth corresponding to an applied voltage of 1 V to the depletion depth corresponding to the maximum applied voltage (200 V or about 80% of the breakdown voltage, whichever is lower). To be measured by this Test Method, a layer must be thicker than the depletion depth corresponding to an applied voltage of 2 V.
 

This Test Method is intended for rapid carrier density determination when extended sample preparation time or high temperature processing of the wafer is not practical.
 

This Test Method provides for determining the effective area of the mercury probe contact using polished bulk reference wafers that have been measured for resistivity at 23°C in accordance with SEMI MF84 (refer to Note 1). This Test Method also includes procedures for calibration of the apparatus for measuring both capacitance and voltage.

Referenced SEMI Standards (purchase separately)
SEMI C28 — Specification and Guide for Hydrofluoric Acid
SEMI C29 — Specification and Guide for 4.9% Hydrofluoric Acid (10:1 v/v)
SEMI C30 — Specification for Hydrogen Peroxide
SEMI M59 — Terminology for Silicon Technology
SEMI MF26 — Test Method for Determining the Orientation of a Semiconductive Single Crystal
SEMI MF42 — Test Method for Conductivity Type of Extrinsic Semiconducting Materials
SEMI MF81 — Test Method for Measuring Radial Resistivity Variation on Silicon Wafers
SEMI MF84 — Test Method for Measuring Resistivity of Silicon Wafers with an In-Line Four-Point Probe
SEMI MF672 — Test Method for Measuring Resistivity Profiles Perpendicular to the Surface of a Silicon Wafer Using a Spreading Resistance Probe
SEMI MF723 — Practice for Conversion Between Resistivity and Dopant or Carrier Density for Boron-Doped, Phosphorus-Doped, and Arsenic-Doped Silicon
SEMI MF1153 — Test Method for Characterization of Metal-Oxide-Silicon (MOS) Structures by Capacitance-Voltage Measurements

Revision History
SEMI MF1392-0307 (Reapproved 1023)
SEMI MF1392-0307 (Reapproved 0718)
SEMI MF1392-0307 (Reapproved 0512)
SEMI MF1392-0307 (technical revision)
SEMI MF1392-1103 (first SEMI publication)