Patent ID: 7435517

Claim:
Method for reducing the fogging effect in an electron beam lithography system, wherein the exposure is controlled in order to obtain patterns resulting after a process to optimize the global CD-uniformity over a whole mask or wafer which is conforming to design data comprising the steps of: exposing proximity corrected test patterns; measuring the geometry of the resulting test structures within the test pattern and thereby obtaining a set of measurement data showing the influence of the fogging effect on the dimensions as required by the design data; determining basic fogging input parameters for a Gaussian or other function, the function type being chosen in accordance with a Kernel type used in a proximity corrector describing the fogging effect, from the set of measurement data; fitting a model for the fogging effect by individually changing at least the basic fogging input parameters of the Gaussian or other function, by considering a proximity effect, to the set of measurement data and thereby obtaining an optimized set of parameters for a single common proximity and fogging control function; and applying the common proximity and fogging control function to an exposure control of the electron beam lithography system during the exposure of a pattern according to the design data, wherein the test patterns are surrounded by an exposed area with a separation gap between the test patterns and the exposure area boundary, and wherein the method further comprises the step of applying the individually changed fogging parameters to a calculation and comparing the calculated results with the set of measurement data.