CIF

CIF (Caltech Intermediate Form) is a plain-text factory drawing from an earlier era that you can open in a text editor.

One polygon, listed by its corners. An older text file stores the corners and little else.

Universities and old flows still emit .cif. Today the format is mostly history and a teaching file. It lists symbols, which are named drawings, then boxes and polygons on numbered layers, in integer hundredths of a micron in the classic dialect. A pad can be read by eye: B 200 200 0 0 is a 2 micrometer square. A class project might be 20 kilobytes of CIF, a small ASCII file beside a modern GDSII binary. The same geometry in GDSII is not more correct; it is more usual. CIF does not carry a rich datatype story, and it is a poor container for a phone-scale chip. OASIS and GDSII took that job. If someone hands you CIF, import it, map the layers to the current process kit, and export a stream the shop will accept.

CIF units do not automatically match the editor’s user unit. Read the header and measure a known box. A factor-of-100 error looks like a correct picture at the wrong size.

The binary file that replaced it, the idea of a layout, and who still reads these drawings are covered in GDSII in plain language, what is a layout, and who reads a layout.