International Business Machines Corporation

Erwin Bretscher

Peter Vettiger

Johann Greschner

Harald Bohlen

Peter Nehmiz

Helmut Engelke

According to this process two partial patterns which, if superimposed upon each other in a predetermined alignment relative to each other yield the desired pattern, with elements of both partial patterns combining to form elements of the pattern, and these partial pattern elements overlapping sectionally, are projected with a suitable radiation onto the radiation-sensitive layers. Overlapping is achieved in that when designing the two partial patterns a pattern corresponding to the desired pattern is used as a basis in that the elements of this pattern are exposed to a negative windage, the negative windage pattern is subsequently partitioned into two negative windage patterns corresponding to the partial patterns, and finally the negative windage partial pattern elements are exposed to a positive windage to the desired size of the partial pattern elements. The method is used in particular when a pattern is to be transferred by means of hole masks, and if it is necessary, e.g. because the pattern shows annular elements, to use instead of one mask only two complementary masks each comprising at least one part of the pattern.

Method of transferring a pattern into a radiation-sensitive layer

A system to improve the uniformness of patterns for LSI circuits or masks generated in an electron beam lithographic system uses a backscatter indicator signal to vary a control signal for the beam stepping rate proportional to the variations in the amount of backscattered electrons. This avoids non-uniformity such as line width variations which otherwise occur when the pattern to be generated covers border lines between two different substrate or base layer materials. Range setting circuitry is provided for adjusting, during an initial prescan of a sample of two materials having an extreme difference in their backscatter characteristic, the offset and the gain for the backscatter detector. During subsequent exposure of a wafer, the backscatter indicator signal and thus the stepping rate control signal variations remain within preselected limits.

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Rapperswil, Switzerland

Erwin Bretscher