US 6,983,444 B2
Mask for reducing proximity effect
Chin Cheng Yang, Hsinchu (Taiwan)
Assigned to Macronix International Co., Ltd., Hsinchu (Taiwan)
Filed on Aug. 01, 2003, as Appl. No. 10/633,070.
Prior Publication US 2005/0026047 A1, Feb. 03, 2005
Int. Cl. G06F 17/50 (2006.01)
U.S. Cl. 716—19 8 Claims
OG exemplary drawing
 
1. A mask for reducing proximity effect, comprising:
a plurality of line-shaped features;
a plurality of groups of first assist features, each group of first assist features positioned between two adjacent line-shaped features, wherein the first assist feature is approximately rectangular in shape and the width of the first assist feature is larger than the length of the first assist feature; and
a plurality of second assist features, each of the plurality of second assist features positioned between one of the plurality of line-shaped features and one group of first assist features, wherein the width of the second assist feature is smaller than two-fifths but larger than one-fourth of the wavelength of an exposure source.