Pattern inspection apparatus and pattern inspection method using the same

A pattern inspection method comprising:

• inspecting a sample with a scanning electron microscope (SEM);
• inspecting a wafer with the SEM;
• and
• inspecting a quality of an SEM image of the wafer,
• wherein the sample comprises a plurality of holes having thicknesses that are different from each other.

A pattern inspection method comprising:

• preparing a wafer and a sample;
• optimizing a condition of an input electron beam incident on the wafer and the sample;
• inspecting the sample with a scanning electron microscope (SEM);
• converting an SEM image of the sample into a first gray level histogram;
• generating a second gray level histogram by correcting a gray level of the first gray level histogram;
• using the corrected gray level, inspecting the wafer with the SEM;
• and
• inspecting a quality of an SEM image of the wafer,
• wherein the sample comprises a plurality of holes having thicknesses that are different from each other.