MASH (Migration Assistant Shape Handler) is a layout manipulation system that allows rapid construction of a design layout solution. MASH is used for various manufacturing and electrical considerations in different stages of the design process, such as technology migration, layout legalization, manufacturing and yield improvement, and performance enhancement. It is developed jointly by IBM Research and IBM EDA and it is being supported by IBM EDA (see Fig. 1).
Figure 1. Mash system flow
MASH consists of several components:
- Layout optimization engine: uses a novel, practical, efficient and effective layout optimization algorithm which handles both flat and hierarchical layouts. The layout optimization is guided by a novel minimum perturbation formulation.
- Ground rule engine: allows a very flexible description of all IBM ground rules.
- Shape manipulation software: MASH uses various shape manipulation software programs to prepare input data for the layout optimization engine.
- API for system integration: provides a set of APIs to facilitate integration with an existing design environment. The API set allows rapid construction of customized design layout solutions. For example, with the set of APIs, users can set up customized layout systems for scaling the layouts in older technology to a new technology, redistributing global wires apart to make use of white space to improve random defect yield, spacing critical nets farther to reduce coupling noise, and resizing devices to improve performance or reduce leakage.
Here is an example of a cell layout migration (see Fig. 2):
Fig. 2 Cell layout migration
MASH is used heavily inside IBM to migrate designs from one generation of IBM technology to the next generation of IBM technology without sacrificing layout density, and to migrate designs from third party's technologies to IBM technologies. The designs migrated by MASH include dataflow macros for IBM S/390, PowerPC and Cell processors, SRAM/DRAM macros and standard-cell libraries for IBM ASIC. It is also used in a DFM (Design For Manufacturability) environment, for example, to support a set of recommended rules. In addition, it has been used to evaluate the density impact of new technologies such as Alternating Phase Shift Mask.
1. F.L. Heng, L. Liebmann, J. Lund, Application of Automated Design Migration to Alternating Phase Shift Mask Design (pdf), 2001 International Symposium on Physical Design, pp. 38-43.
2. Z. Chen and F.L. Heng, A Fast Minimum Layout Perturbation Algorithm for Electromigration Reliability Enhancement (summary), The IEEE International Symposium on Defect and Fault Tolerance in VLSI Systems, 1998, pp. 56-63.
3. F.L. Heng, Z. Chen and G. Tellez, A VLSI Artwork Legalization Technique Based on a New Criteria of Minimum Layout Perturbation (pdf), 1997 International Symposium on Physical Design, pp. 116-121.
Last updated August 15, 2007