Addressing EUV masks registration challenges through closed loop correction
Avi Cohen1, Ofir Sharoni1, Dirk Beyer2, Christian Ehrlich2
1Carl Zeiss SMS Ltd. Karmiel , Hadolev 3, 20156 Bar Lev Industrial Park, Israel
2Carl Zeiss SMT GmbH, Carl-Zeiss-Promenade 10, 07745 Jena, Germany
ABSTRACT
EUV lithography is expected to become a critical enabling technology in the short and mid future of high end IC manufacturing. Although much effort is going into process and manufacturing challenges and inroads are being made in the industry, some process residuals will still exist with the move to HVM and among them will be the mask registration errors and the on product overlay (OPO).
The PROVE® system is the state of the art high end registration metrology tool capable of measuring both DUV as well as EUV masks. The ForTune® EUV utilizes an ultra short pulse laser to modify the mask substrate in order to correct registration errors and bring the mask into specification. Combining the metrology capabilities of the PROVE® with the corrective capabilities of the ForTune® EUV allows a closed loop solution in which the registration metrology data is utilized to feed forward the correction job needed to be applied over the mask in the ForTune® EUV.
This paper investigates the ability to improve mask registration on EUV masks using closed loop feedback between the PROVE® and ForTune® systems. Initial registration data from an EUV mask is measured by the PROVE® and utilized to both calculate the mask tuning job as well as predict the improvement prior to actual procession. After carrying out the registration correction on the ForTune® EUV, the EUV mask is again measured on the PROVE® to evaluate the ForTune® EUV process
The registration is measured with the PROVE® and the data is utilized by the Advanced Tuning Center, a FAVOR® solution, to prepare the job for the ForTune® EUV correction.
KEYWORDS: EUV, ForTune®, PROVE®, EUV mask, overlay correction, registration correction,