Going from GDSII to OASIS

It's a banality to say that nowadays, databases for digital chips are more than huge. The physical description of an SOC, encoded in the classical GDSII format, now often goes over 20Gbytes. Files of up to 200Gbytes have been reported by mask houses. Even if storage systems and data transfer links can handle such sizes, it is obvious that such big files are difficult to manipulate.

GDSII was introduced by Calma in 1978 as a successor of GDS format created in 1971. Since almost 30 years, no major change have been made to this de-facto standard while chips complexity was multiplied by as much as 106. In addition to file size issue, numerical values needed to describe geometries of nanoscale structures on 300mm wafers will soon reach the 32 bits limits of GDSII format.

The OASIS format was developed to address such issues and its first official specification was released in 2004 [1].

This article describes how size and precision limitation issues are managed in OASIS format. It also singles out some critical points of this format and finally gives some ways to really get full benefits from OASIS and to circumvent potential pitfall and problem using this new standard.

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