Electron beam lithography simulation based on a single convolution approach - Application for sub-45nm nodes

Electron Beam Direct Write (EBDW) is involved today in advanced devices manufacturing and technology node development. As a consequence, EBDW is supporting an increasing number of technologies and several layers per technology. In this context, an EBDW simulator can strongly help this development study and reduce process development cycle time. Today, available EBDW simulators are based on the use of a Point Spread Function (PSF) to describe the energy absorbed into the resist during exposure and resist models. Beside a constant improvement of these models limitations are observed in simulation of sub-45nm nodes. In this paper, several simulation methods are investigated with the purpose to build a simulation method relevant for sub-45nm nodes. The limitations of classical EBDW simulation based on a full process flow simulation are evaluated for line width below 100nm. Then, a reduced process flow simulation limited to the exposure step is investigated with the use of both a simulated PSF and an empirical PSF. We will see that the approach to use an empirical PSF with the reduced process flow simulation has good predicting capabilities in simulating structures down to 40nm.