Photomasks having sub-lithographic features to prevent undesired wafer patterning

摘要

A photomask that is used as a light filter in an exposure system is made of at least one layer of material comprising one or more transparent regions and one or more non-transparent regions. The difference between the transparent regions and the non-transparent regions defines the features that will be illuminated by the exposure system on a photoresist that will be exposed using the exposure system. The features comprise one or more device shapes and at least one sub-lithographic shape that will be exposed upon the photoresist. The sub-lithographic shape has an sub-lithographic shape size that is limited in such a way that the sub-lithographic shape causes a physical change only in a surface of the photoresist. Therefore, because the sub-lithographic shape is so small, it avoids forming an opening through the photoresist after the photoresist is developed and only causes a change on the surface of the photoresist.