Determination of proximity effect parameters and the shape bias parameter in electron beam lithography

Abstract

For CD (critical dimension) control with high accuracy, it is important to correct the proximity effect as well as to compensate the shape bias in electron beam lithography (EBL). In this work, we propose a method for determining the proximity effect parameters and the shape bias parameter concurrently. Due to the beam current instability of the E-beam writer, it is difficult to determine the parameters of the forward scattering range by delineating sub-0.1 mu m patterns. Accordingly, it is important to determine the proximity effect parameters without the errors that can occur in delineating sub-0.1 mu m patterns. Though the pattern bias has a small value such as tens-nm, it affects the CD control at sub-micron regime. For demonstrating the accuracy of the parameters, proximity effect correction (PEC) is carried out using the conventional dose modulation method after shape bias compensation. The variation of CD errors for Lines and Spaces (L&S) patterns with PEC is less than 4% using the obtained parameters.