Desired IP Control methodology for EUV Mask in Current Mask Process

Abstract:
Extreme ultra-violet (EUV) lithography is one of the leading potential solutions for next generation lithography. Image placement (IP) errors specific to EUV mask induced by non-telecentricity have to be minimized to satisfy the strict IP requirement. IP accuracy of EUV mask is considerably influenced by electro-static chuck (ESC) characteristics and backside non-flatness of each blank when it is held by ESC in EB mask writer, IP metrology tool, and exposure tool as suggested in SEMI standard. We propose to apply the correction technique to each EUV mask in EB mask writing with flatness data of blank and ESC to minimize IP errors caused by mask non-flatness and ESC characteristics. In addition, IP control methodology for EUV mask with conventional IP metrology tool is proposed for pattern writing by EB mask writer with this correction technique. Early development of EUV mask patterning is enabled by this IP control methodology without substantial changes to the current mask process.