Mask data preparation

Mask data preparation (MDP) is the procedure of translating a file containing the intended set of polygons from an integrated circuit layout into set of instructions that a photomask writer can use to generate a physical mask. MDP usually involves mask fracturing where complex polygons are translated into simpler shapes, often rectangles and trapezoids, that can be handled by the mask writing hardware. Because mask fracturing is such a common procedure within the whole MDP, the term fracture, used as a noun, is sometimes used inappropriately in place of the term mask data preparation. The term fracture does however accurately describe that sub-procedure of MDP.

Typically, mask data preparation requires an input file which is in a GDSII or OASIS format, and produces a file that is in a proprietary format specific to the mask writer.

MDP Procedures

Although historically the fracture translation task was relatively simple, more recent MDP procedures require the additional steps of resolution enhancement technologies (RET) and optical proximity correction (OPC), steps associated with design for manufacturability. Special considerations in each of these steps must also be made to mitigate the negative affects associated with the enormous amounts of data they can produce; too much data can sometimes become a problem for the mask writer to be able to create a mask in a reasonable amount of time.

References

• Electronic Design Automation For Integrated Circuits Handbook, by Lavagno, Martin, and Scheffer, ISBN 0-8493-3096-3 A survey of the field, from which this summary was derived, with permission.