Electron-beam-based photomask repair

High-resolution electron-beam-assisted deposition and etching is an enabling technology for current and future generation photomask repair. NaWoTec in collaboration with Carl Zeiss NTS (formerly LEO Electron Microscopy) has developed a mask repair tool capable of processing a wide variety of mask types, such as quartz binary masks, phase shift masks, extreme ultraviolet masks, and e-beam projection stencil masks. Specifications currently meet the 65 nm device node requirements, and tool performance is extendible to 45 nm and below. The tool combines LEO's ultra-high-resolution Supra scanning electron microscope platform with NaWoTec's proprietary e-beam deposition and etching technology, gas delivery system, and mask repair software. In this article, we focus on tool performance results; that is, the reproducibility and accuracy of repair of clear and opaque programmed defects on Cr binary and MoSi phase shift masks. These masks have in the past been difficult to repair due to beam position instability caused by charging of the insulating quartz areas. We have found and implemented a solution to this charging problem and have demonstrated in spec repair of various defect types. The extendibility of e-beam-based repair technology to future lithography nodes, both in terms of the required resolution and the ability to repair next generation lithography mask types, will also be addressed. (C) 2004 American Vacuum Society.