Photomask Japan 2009

Yoshinori Hagio*, Ichirota Nagahama, Yasuo Matsuoka, Hidefumi Mukai and Kohji Hashimoto

Process & Manufacturing Engineering Center, Toshiba Corporation, Semiconductor Company
8, Shinsugita-cho, Isogo-ku, Yokohama 235-8522, Japan

ABSTRACT

Turn around time (TAT) of mask qualification is one of the most important factors for high-end mask installation to LSI production lines. Accurate mask qualification with shorter TAT for mask process updates brings about steep rampup of LSI volume production. In this paper, an innovative approach is described for mask qualification with a die-todatabase (D2DB) inspection system that can accomplish both qualification accuracy and short TAT in low k1 lithography.

The D2DB inspection system, NGR2100[1], has features satisfying the above requirements owing to larger field of view (FOV) and higher probe current than those of CD-SEM. Compared with the conventional optical inspection tool, the system provided higher accuracy in extracting fatal defects called “hotspots”. Also, hotspots extracted by the system covered all killer hotspots extracted by electrical and physical analysis [2].

The contours of hotspots extracted by NGR2100 are transferred to GDS data format to compare hotspots between conventional mask process and updated mask process. If the differences between the contours are within an assumed tolerance, the system provides the qualification for updated mask process. As a result, qualification TAT was reduced by as much as two months compared with the conventional electrical qualification on wafers.

Keywords: Mask qualification, Die-to-database inspection, Hotspot management, DFM