Patent ID: 7777483
Filing Date: 2010-08-17
Classification: G01B

Abstract:
1. An apparatus for dynamically measuring a thickness of a layer of a wafer, comprising: an eddy current sensor having first and second sensor heads, said sensor heads positioned substantially opposite each other and defining a predetermined gap therebetween for passage by at least a portion of said wafer, said eddy current sensor configured to cause said first and second sensor heads to make measurements at a plurality of sampling locations on said wafer while said wafer is moving through said gap, said eddy current sensor including a circuit to generate an AC current to drive the first and second sensor heads at a frequency, and wherein the first and second sensor heads are connected in series to the circuit; a robotic end effector configured to hold said wafer and move said wafer linearly through said gap while said measurements are made so that said measurements are made at said plurality of sampling locations along a line across said wafer; and a controller connected to said eddy current sensor, said controller configured to determine said thickness of said layer of said wafer at said plurality of sampling locations from said measurements by said first and second sensor heads.