15.01.2013 Views

U. Glaeser

U. Glaeser

U. Glaeser

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

FIGURE 47.10 Scan-lines with rectangles in the active list.<br />

FIGURE 47.11 Software system for extraction of IC critical areas.<br />

its next stopping position is S2. Now the newest rectangle in the active list is the rectangle 7. In the same<br />

time, the rectangle 4 exits the active list because the spacing between its bottom edge and the current<br />

scan-line is greater than a threshold value (x max). By making use of the described algorithm, the critical<br />

areas related to point and lithographic defects for any IC can be extracted.<br />

Implementation and Performance<br />

The layout extraction starts from the layout description in CIF format and ends by reporting the critical<br />

areas for point or lithographic defects. In our case, this procedure is done through software system, which<br />

consists of three tools. The previous algorithm is only dedicated to the back-end of the entire system and<br />

is implemented in a program called EXACCA (EXtrActor of Chip Critical Area). The structure of this<br />

system is shown in Fig. 47.11.<br />

Transformer of CIF (TRACIF)<br />

The front-end of system is a technology-independent processor for transforming IC layout description<br />

from the unrestricted to a restricted format TRACIF [63]. The unrestricted format can contain overlapping<br />

rectangles, as well as rectangles making bigger rectangles from the same IC mask layer; however,<br />

an internal restricted geometric representation should contain a set of nonoverlapping rectangles that<br />

about only along horizontal edges. Two important properties are part of the restricted format:<br />

• Coverage—Each point in the x-y plane is contained in exactly one rectangle. In general, a plane<br />

may contain many different types of rectangles.<br />

• Strip—Patterns of the same IC mask layer are represented with horizontal rectangles (strips) that<br />

are as wide as possible, then as tall as possible. The strip structure provides a canonical form for<br />

the database and prevents it from fracturing into a large number of small rectangles.<br />

© 2002 by CRC Press LLC

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!