Variable proximity corrections for submicron optical lithographic masks

Exposure requirements for size control of high density features results in overexposure of isolated or low density lines and features. Use of positive photoresist results in low density feature shrinkage under these conditions. This paper presents a simple methodology of automatic addition of variable biasing to features depending on local circuit density using software manipulation of the circuit design data base. This methodology extends the practical usefulness of optical lithography to submicron circuit fabrication. Results show that use of variable proximity corrections nearly doubles the practical resolution of the DSW system utilized in this study.