Monitoring system of CD error analysis for the 90-nm node mask manufacturing

Abstract

CD(Critical Dimension) Non-Uniformity on a mask is normally separable into global and local CD errors by means of their error sources. In general a global CD error trend on a mask shows the properties of each process. On the other hand, local CD errors on a mask are pretty much random and caused from mainly measurement errors, LER(Line Edge Roughness), and litho-shot errors. However, because of its difficulty to pin point the sources of errors and correct them, the local CD errors are required more attention. A Global CD error trend on a mask can be classified into several groups. One originating from vacuum delay, lithography error, bake and etch process will cause a side error trend on a mask. Others are fogging, radial trends of develop, and etch loading. In order to classify all those global CD errors and local CD errors, the proper monitoring mask must be required. The works on this paper mainly focalize on minimizing global CD error trends on a mask by separating and analyzing error components with proper monitoring system of each process. We therefore, provide a monitoring mask designed for efficiently representing global and local CD errors in more detailed fashion which can analyze CD errors of each process and make feed-back to each process in order to improve each process of mask manufacturing.