Method and control arrangement for the evaporation rate of an electron

Abstract

The average evaporation rate over a predetermined area to be evaporated is controlled by moving an electron beam over said area wherein one characteristic of the electron beam is controlled in order to influence the evaporation rate. The electron beam is moved along a path according to stored maps wherein each position to which the electron beam is moved has assigned thereto substantially equal control values. In a first technique, each of the individual stored maps are selected in a sequential fashion to minimize the number of changes in the control value during a complete scan of the area being evaporated. In another technique, the control value of a predetermined position is compared against a predetermined number of stored control values, which is preferably all of the control values stored in a memory. The position data having associated control values which differ from the control value of the predetermined position by a predetermined minimal amount are stored as a map and thereafter utilized to control the electron beam so that the characteristic of the electron beam being controlled is maintained substantially constant for all of those positions stored as a map. In still another technique, a plurality of maps are stored in a memory, each map comprising position data whose associated control values are substantially equal and wherein two or more of said maps are selected and the control values of the maps associated with the same position are combined to control a characteristic of the beam.