In semiconductor manufacturing, control of hotspots by optical proximity correction (OPC) requires
accurate measurements of shapes and sizes of fabricated features. These measurements are carried
out using CD-SEM. In order to measure 2D shapes, edges of features should be clearly defined in all
directions. Positions of edges are often unclear because of charging. Depending on the SEM setup and
the pattern under measurement, the effect of charging varies. The influence of measurement conditions
can be simulated and optimized. A Monte Carlo electron-beam simulation tool was developed, which
takes into account electron scattering and charging. CD-SEM imaging of SiO2 lines on Si were studied.
In experiment, an effect of contrast tone reversal was found, when beam voltage was varied. The same
effect was also found in simulations, where contrast reversal was similar to the experimental results. The
time dependence of contrast variation was also studied. A good agreement between simulation and
measurement was found. The simulation software proved reliable in predicting SEM images, which
makes it an important tool to optimize settings of electron-beam tools. Based on such simulations,
optimum conditions of SEM setup can be found.
A fine pixel CD-SEM system is developed. The convnetional CD-SEM Topcon MI-3080UR system consists of main body, 512 pixel SEM image acquisition system and 1D pattern size measurement system. The fine pixel CD-SEM system is added the conventional CD-SEM TOPCON MI-3080UR system. The fine pixel CD-SEM system consists of 2048pixel SEM image acquisition system is used by adjusting a novel measurement algorithm for the SEM image of 2D patterns. Firstly, the necessity of the fine pixel CD-SEM is discussed from the viewpoint of getting good repeatability of pattern size measurements. Effective factors causing the good repeatability for pattern size measurements are studied. The effective factors are mainly SEM image quality and pattern measurement algorithm. Secondly, repeatability of 2D pattern measurements by using the developed fine pixel CD-SEM image and the novel algorithm are evaluated. The evaluated 2D patterns are used for hammer head type OPC patterns for DRAM cell pattern. Finally, we investigate the usefulness of the fine pixel CD-SEM by usign the same novel algorithm for comparison of the conventional and the fine pixel CD-SEM.