Novel process for phase-shifting mask fabrication

Abstract

In this new process for phase-shifting mask fabrication, molybdenum silicide (MoSi) is used as an optical shield layer and spin-on glass (SOG) as a phase-shifter layer. Chromium is employed as an etch-stopper during SOG etching. Cr etch-stopper will be removed at the end of the process, therefore all optical problems related to an etch-stopper are avoided. This Cr etch-stopper is also useful in inspection and repair of shifter remaining defects. At first, we will describe the fabrication process including the shifter-defect inspection and repair.Secondary, we will discuss the phase-shifting mask accuracy and its influence to the printed resist pattern when using the alternating type phase-shifting mask. Lastly,we will mention the application result of development of lithography for 64Mbit DRAM using this process.