Technique for estimating the angle of incidence and depth of focus of an electron beam

Abstract

In order to cope with the problems with scanning electron microscopes for semiconductor manufacturing, the ability to measure the focal depth and incident angle of an electron beam is required. A technique for estimating the angle of incidence and the depth of focus has been devised. The main feature of the technique is to employ the specimen with a special pit, which is formed from sidewalls with an accurate tilt angle and a surface structure. In this work, the pit was formed on a (100) silicon-crystal substrate and from four (111) sidewalls with an accurate tilt angle of 54.74° and a step-like surface. The incident angle and focal depth of an electron beam was estimated by using the pit. The estimation result agreed approximately with the expected.