A CP Mask Development Methodology for MCC Systems

The character projection (CP) is utilized for maskless lithography and is a potential for the future photomask manufacture because the CP can project ICs faster than the point beam projection and the variable-shaped beam (VSB) projection. The drawback of the CP is its lower throughput than that of photomask-based lithography and the amortization cost of CP equipment leads to the price rise of ICs. This paper discusses a CP mask development methodology for increasing the throughput of MCC systems. The proposed methodology virtually increases the number of the logic cells which are projected with the CP. In the proposed methodology, the multiform CP masks are utilized among the column-cells for reducing the VSB projection. The experimental results show that the proposed CP mask development methodology reduced 71.3% of the number of EB shots needed for an SCC system. It also reduced 42.6% of the number of EB shots needed for the MCC system in which uniform CP masks are utilized for all column-cells.