A new approach of e-beam proximity effect correction for high-resolution applications

The e-beam proximity effect is well known as one of the limiting factors in e-beam lithography, As features get smaller the need for e-beam proximity effect correction (EPC) increases. There exist different approaches to cove r these effects by varying dose or shape of the pattern layout during the e xposure step. Both of these basic approaches have drawbacks limiting their application. For example, the EPC correction by shape variation underlies c onstraints such as neighbouring features, the exposure grid of the e-beam t ool and writing time. EPC by dose variation fails in cases the feature size is very close to the process dependent forward scattering parameter alpha. To guarantee CD uniformity in these cases a negative dose assignment would be necessary, which is practically impossible. The paper presents a new co rrection scheme based on dose assignment and geometry variation at the same time. After a short introduction the theoretical description of the method is given. Dose and geometry modifications are calculated using a Fast Four ier Algorithm. Due to the ability of changing the geometry depending on fea ture size and feature neighbourhood even very small features can be printed correctly, This flexibility is the main advantage compared to already exis ting methods. Pattern fidelity and linearity can be improved drastically, R esolution limits can be pushed further down. The application of the automat ic correction to high resolution features with a feature size of 100 nm are demonstrated. The CD linearity is investigated and demonstrated using a re al device patterns.