For feature sizes smaller than 100 nm, proximity effect correction gains more importance in electron beam lithography. Several methods have been proposed for the determination of the proximity parameters, most of them being extensive and time-consuming. This paper investigates the reliability of the doughnut test and specifies the electron backscattering portion with a given resist-process. The functionality of the method for negative resist systems exposed by a variable shaped e-beam writer is shown for the first time. Compared with conventional methods, the modified doughnut test was proven to be a fast, straightforward and reliable method for determining the backscattering proximity parameters when utilized together with sensitive scanning electron microscopy.