Scatterometry metrology challenges of EUV

Resolution enhancement techniques such as double patterning (DP) processes are implemented to achieve lower critical dimension (CD) control tolerances. However the design complications, overlay resulting from multiple exposures, and production cost limit the DP usage. EUVL offers the most promising patterning technology to be adopted for 14nm and beyond due to simplicity and cost advantage estimates. However, EUVL is also prone to number of patterning challenges that are unique to EUV, such as orientation dependent pattern placement errors resulting from mask shadowing effect, flare(leads to CD non-uniformity) and non-flatness (leads to overlay errors). Even though the shadowing effects can be corrected by means of OPC and mask stack design, there is a need to monitor the systemic errors due to HV bias in order to control the lithographic process. In this paper, we will report the measurement sensitivity of EUVL targets (CD, height and sidewall angle), systemic CD errors (H-V bias) and feedback for OPC correction by scatterometry. We will also report the measurement precision, accuracy and matching for EUV structures.