HIGH SENSITIVITY REAL TIME PROFILE CONTROL EDDY CURRENT MONITORING SYSTEM

摘要

An apparatus for chemical mechanical polishing includes a platen having a surface to support a polishing pad, and an eddy current monitoring system to generate an eddy current signal. The eddy current monitoring system includes a core and a coil wound around a portion of the core. The core includes a back portion, a first prong extending from the back portion in a first direction normal to the surface of the platen and having a width in a second direction parallel to the surface of the platen, and second and third prongs extending from the back portion in parallel with the first protrusion, the second and third prongs positioned on opposite sides of and equidistant from the first prong. A spacing between each of the second and third prongs and the first prong is approximately equal to twice the width of the first prong.