Patent ID: 6681379
Filing Date: 2004-01-20
Classification: G03F

Abstract:
A method for producing a computer readable definition of a photolithographic mask that defines a pattern in a layer to be formed using the mask, wherein the pattern includes a plurality of features corresponding to a plurality of static random access memory (SRAM) cells, the plurality of features including two opposing T-shapes in a field for each SRAM cell, the T-shapes generally shaped like a T, a T-shape having a top with a back, and a bar, the top and the bar forming inside comas, and having a contact on the bar, the method comprising:selecting a cutting pattern from a set of patterns including at least (i) a first cutting pattern comprising a first cut between two contacts of each SRAM cell and a second and third cuts, the second and third cuts on inside corners of the T-shapes of each SRAM cell opposite the first cut, (ii) a second cutting pattern comprising a first cut between two contacts of each SRAM cell and a second cut on the back of the T-shape of each SRAM cell to the back of a T-shape of an adjacent SRAM cell, (iii) a third cutting pattern comprising a first cut and a second cut from contacts of the SRAM cell to the field and a third cut on the back of the T-shape of the SRAM cell to the back of a T-shape of an adjacent SRAM, and (iv) a fourth cutting pattern comprising a first cut and a second cut extending respectively from opposing inside corners of one of the two T-shapes of each SRAM cell to the contacts on the bars of the other of the two T-shapes of each SRAM cell, for use in defining the plurality of SRAM cells; and defining a plurality of phase shifters in the computer readable definition of the mask to fully define the plurality of SRAM cells using destructive light interference, wherein the plurality of phase shifters separated by cuts according to the cutting pattern.