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7
Resistivity and Impurity Concentration
Mapping of Silicon Wafers
7.1 Introduction
Dopant impurities play a key role in semiconductor device operation, as they directly
inuence the electrical properties of different regions. The dopant concentration
directly affects the parameters such as the threshold voltage in metal-oxide semicon-
ductor (MOS) very large scale integration (VLSI) transistors and breakdown voltage of
the devices fabricated. During silicon crystal growth, the impurity atoms with k
o
value
(i.e., equilibrium segregation coefcient) less than 1 are rejected by the advancing solid
at a greater rate than they can diffuse into the ...