Enhanced Hole Shape of Flash Devices in ArF Lithography by Eliptical Mask Bias Technique

摘要

As the resolution requirement downing 90 nm beyond, hole pattern is one of the most challenging features to print in the semiconductor manufacturing process. Especially, when hole patterns have dense array of holes as they are consisted of several columns with single row, there can be serious distorted form from desired patterns such as oval hole shape and bridge between holes. It is due to nature of diffraction which generates interaction of diffracted light from near holes. Overlap margin reduction by hole shape change as oval shape is very harmful in sub-90nm photolithography process which has very narrow overlay margin. To increase overlap margin, it is necessary to solve these phenomenon. Optical Proximity Correction (OPC) has been used for overcoming oval hole shape. Through the result of OPC modeling and simulation, we could get optimized mask bias of hole. Sometimes, good experimental data will be help for this modeling and OPC process. From these OPC simulation and experimental data, most compatible rule based OPC process could be developed. In this paper, we suggest the method of improving oval hole shape by using OPC simulation and making rule base OPC process from experimental data.