Simultaneous flooding and inspection for charge control in an electron beam inspection machine

摘要

Disclosed are methods and apparatus for simultaneously flooding a sample (e.g., a semiconductor wafer) to control charge and inspecting the sample. The apparatus includes a charged particle beam generator arranged to generate a charged particle beam substantially towards a first portion of the sample and a flood gun for generating a second beam towards a second portion of the sample. The second beam is generated substantially simultaneously with the inspection beam. The apparatus further includes a detector arranged to detect charged particles originating from the sample portion. In a further implementation, the apparatus further includes an image generator for generating an image of the first portion of the sample from the detected particles. In one embodiment, the sample is a semiconductor wafer. In a method aspect, a first area of a sample is flooded with a flood beam to control charge on a surface of the sample. A second area of the sample is inspected with an inspection beam. The second area comprises at least a portion of the first area flooded by the flood beam. The inspection beam moves in tandem with the flood beam.;In another aspect of the present invention, methods and apparatus are provided for controlling the charge buildup of an area of the sample by an electrode having a voltage applied to it and through which the flood beam and charged particles emitted from the area of the sample can pass.