A Color Graphics System for I.C. Mask Design and Analysis

In view of the continuing requirement for good interactive tools in the area of computer aided design, an advanced high-resolution monochrome and color, minicomputer controlled, graphics display has been designed and built. Considering the particular area of integrated circuit mask design, the ability to produce filled, color coordinated shapes extends the designer's interpretation of displayed layouts to a level not previously available with conventional graphics displays. Apart from this welcome improvement in interpretation, the hardware structure of the display provides the system designer with a tool which is potentially far more powerful than existing displays. This factor has been used to implement a comprehensive system to design MOS IC layouts in a detailed manner at the device level. A resulting program is described which is capable of deriving the node table, transistor parameters and parasitic effects for a MOS circuit displayed on the graphics monitor. The output format of this program is in a form suitable for direct input to a general circuit analysis program. The algorithms which use a topological mapping approach are shown to have possible execution time benefits over previous methods while maintaining the overwhelming advantage of user interaction. The relationship of this approach to more automated systems is also treated.