1. Project introduction:

SRP (Spreading resistance profile) diffusion resistance analysis is a technique used to analyze the relationship between resistivity and depth in semiconductors. Semiconductor devices rely on the distribution of carriers (electrons or holes) in their structure to provide the desired performance. The concentration of carriers, which can vary by orders of magnitude, can be inferred from the resistivity curve provided by the SRP.

Diffusion resistance distribution is a method for testing electrical parameters such as diffusion resistance, resistivity, carrier concentration distribution and other electrical parameters of semiconductor materials with higher resolution, which belongs to an experimental comparison method, the step of the method is to first measure the extended resistance of a series of point contacts (Rs is the ratio of the potential drop between the conductive metal probe and a reference point on the silicon wafer to the current flowing through the probe), and then use the calibration curve to determine the resistivity of the measured sample near the probe contact point, and then convert it into the carrier concentration corresponding to the series of test points.

In order to improve the spatial resolution, and according to the target measurement depth, the cross-section direction of the sample can be ground into a series of angles, and the change of resistivity within 5 nm of the depth direction can be measured after the silicon wafer is sharpened.

2. Test instructions:

(1) Determine the type of material: Si, InP, GaAs, SiC, etc

(2) Determine the type of doping: n or p type

(3) Determine the crystal direction type: the crystal direction corresponding to the front side, for Si<001>, <111 >

(4) Doping concentration range: equipment test range 1E11~1E21cm-3

(5) Positioning test position: mark the starting position after grinding the piece, and locate it with the help of optical microscope or SEM

(6) Determine the chip structure: The depth of the chip structure and the minimum internal characteristics are determined by the selection of the grinding angle

(7) Note: The test chip SRP requires the metal layer to be removed to prevent contamination of the section during the grinding process

3. Technical advantages:

The extended resistance method can test the spatial distribution of carrier concentration in epitaxy, diffusion and injection processes such as Si, InP, GaAs, SiC, etc., and has become one of the more important testing methods in the preparation and production of semiconductor materials.