A Practical CAD System Application for Full Custom VLSI Microcomputer Chips

This paper presents a practical CAD system application for layout and verification, resulting in producible full-cutom VLSI microcomputer chips. The CAD system supports three design methodologies--symbolic layout mixed with mask level layout, compaction as an optimizer, and fully automated verification. For the area optimization, the symbolic layout and compactor subsystem supports a flexible description of orthogonal layout patterns with arbitrary dimensions in a loose placement manner. The layout patterns include path data, polygonal data, and symbolic cells. For power and delay optimization, the compactor compacts layout data, decreasing both resistance and capacitance for wires and ion-implanted layers. This feature is pioneering the new generation compactor. Emphasis should be put on the fact that it can compact layout data to a format 10-15 percent smaller than that accomplished manually. The verification subsystem can detect all kinds of errors, more than 30 items. A novel feature of the electrical rule check is that it investigates complementary logic errors for CMOS circuits. The synergy of those three design methodologies has brought about several significant advantages. One is manpower reduction by more than half, in the most complicated design process for unique random logic. The other is a 1600-transistors compaction output, smaller by 365 mils² than that manually compacted. The circuit implementation on a chip works at more than a 15-MHz clock rate. Another is the first silicon success. It has been accomplished in a full-custom VLSI microcomputer chip consisting of more than 100 000 transistors.