Method of determining confidence level of body iron test value

Abstract

The invention provides a method of determining the confidence level of a body iron test value, and relates to the technical field of semiconductor chip processes. Based on determination of the confidence level of the body iron value by comparison of minority carrier diffusion lengths before and after illumination of a silicon wafer to be measured, a difference between a coefficient of association of a body value of a credible silicon wafer and the minority carrier diffusion lengths before and after illumination and a coefficient of association of the body iron test value of the silicon wafer to be measured and the minority carrier diffusion lengths before and after illumination is compared, thus determining the confidence level of the body iron test value of the silicon wafer to be measured. The method effectively determines the confidence level of the body iron value, provides credible experiment data for analysis of process data and accelerates the speed of optimizing process parameters.

Description

technical field [0001] The invention belongs to the technical field of semiconductor silicon wafer technology, and specifically relates to a method for judging the reliability of a body iron test value. Background technique [0002] With the development of IC industry, higher and higher requirements are put forward for the quality of silicon materials. The non-equilibrium minority carrier lifetime (minority carrier lifetime) in silicon single crystal is an important physical parameter that characterizes the performance of materials. One of the main factors affecting the minority carrier lifetime is metal contamination. Because metal impurities can diffuse from the surface of the silicon wafer into the interior through the thermal process, and become a very effective recombination center, which greatly promotes the recombination of carriers, reduces the life of the silicon wafer, and affects the performance and reliability of the device. [0003] In the manufacturing proces...

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Problems solved by technology

[0007] However, the SPV method is an indirect test of the bulk iron concentration in the silicon wafer. During the test, it is easily affected by various factors such as stress caused by the deformation of the silicon wafer, oxygen donors, and the thickness of the surface oxide layer. Therefore, the reliability of the test value needs to be checked. to evaluate

At present, the main basis for judging the reliability of the body iron value obtained by the SPV method is to compare whether the minority carrier diffusion length before illumination is greater than the minority carrier diffusion length after illumination. Body iron test values ​​at diffusion length are sometimes unreliable

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