Sheet resistance mapping has become an indispensable tool in characterizing ion implanters for both integrated circuit manufacturers and equipment manufacturers. The sheet resistance mapping technique is now being extended into additional applications such as the characterization of metal deposition, CVD, and epitaxial silicon growth. This technique has become especially necessary with the advent of 150mm and 200mm wafers, where 5 or 9 site measurements cannot provide sufficient data essential for process control.
In order to optimize the performance of an epi reactor it is necessary to control and characterize the gas flows and temperature distributions inside the reactor. The control of these variables is essential for thickness and resistivity uniformity in epi layers. This paper describes the use of sheet resistance profiles and contour maps to study the resistivity and thickness uniformity variations in an epi reactor. The sheet resistance maps allow for control of the epi process without requiring data from other test sources.This ensures real time process control for production, as well as very rapid feedback for maintenance while doing equipment repair.