Reticle intensity-based critical dimension uniformity to improve efficiency for DOMA correction in a foundry

Abstract

As transistor dimensions shrinks, the requirement for wafer critical dimensions control is becoming increasingly challenging. The intra-field critical dimension uniformity (CDU) of the features on the reticle is one of the many sources of wafer CD variation. In this paper, we study how the CDU on the reticle can be obtained by using the intensity information collected during reticle inspection (iCDU TM ) on the KLA-Tencor TeraScan reticle inspection tool. The collected CDU information of the reticle is then applied as an intra-field dose correction function to improve wafer intra-field CD uniformity.Using this method of extracting the reticle CDU from the intensity information allows for simple integration into a high-volume production environment and an improved capability for intra-field CDU correction without the need to expose any wafers for CD measurement nor any GDS design information. The ability to apply iCDU on prototype devices on first pass run can also accelerate device development.

Intra-field CDU map correlation between SEMs and aerial image characterization

“…To meet the future CDU control specifications, improvements throughout the entire reticle and lithography chain are needed. Intrafield CDU has been reported to be a significant contributor to total CDU [1] [2][3] [4]. There are two basic techniques to improve intra-field CDU.…”