Improving registration measurement capability by defining a 2D grid standard using multiple registration measurement tools

Currently all LMS IPRO pattern placement metrology tools are calibrated using a 1D length standard provided by a national standards institute (e.g. NIST or PTB), however there are no 2-D standards available with an uncertainty matching the requirements of mask manufacturing for the 22nm HP node and beyond. Therefore, the 2D stage coordinate system of the LMS IPRO systems is calibrated using KLA Tencor's proprietary combined correction technique. With introduction of the LMS IPRO4 into high volume mask production at the AMTC, AMTC and KLA-Tencor MIE have demonstrated the capability to match IPRO3 and IPRO4 grids within 1.2 nm uncertainty [1]. Using the Golden Tool approach, we achieved a significant improvement in pattern placement measurement capability of previous generation measurement tools of up to 30%. This in turn leads to improved pattern placement metrology fleet capability and extended useful lifetime of capital equipment. The use of multiple high end registration measurement tools enables the creation of a 2D coordinate system standard, which could be used for improved fleet matching and would help improve the capability of older generation pattern placement metrology tools by matching to this standard. Within this paper Golden Tool and Round Robin worldwide fleet matching approaches are compared and discussed.