High-precision CD measurement using energy-filtering SEM techniques

Voltage contrast (VC) images obtained using an energy filter (EF) were used to measure the bottom surface of high-aspect- ratio (HAR) structures. The VC images obtained using the conventional EF were sensitive to variations in wafer potential. Since CD-SEM metrology requires precise EF voltage control when using VC images, we developed an EF voltage correction method to be used at each measurement point. Consequently, bottom-edge measurement, independent of the wafer potential fluctuations, was achieved by using the newly developed EF. Our developed technique is effective for CD-SEM metrology using VC images.