An Approach to MCM Routing in Manhattan Diagonal Model.

Date of Submission

December 2002

Date of Award

Winter 12-12-2003

Institute Name (Publisher)

Indian Statistical Institute

Document Type

Master's Dissertation

Degree Name

Master of Technology

Subject Name

Computer Science


Advance Computing and Microelectronics Unit (ACMU-Kolkata)


Das, Sandip (ACMU-Kolkata; ISI)

Abstract (Summary of the Work)

With the rapid increase of feature size, efficiently packing multiple circuit modules in a single chip has become a promising area of research. Using MCM technology a large number of functional blocks can be mounted and interconnected in a single substrate. The number of distinct nets and terminals are usually very high. A typical MCM may consist of 7000 nets on a grid size of ovcr 2000 X 2000 [2). With the cmergenee of deep sub micron technology the number of chip, nets and terminals per net, in an MCM are likely to increase in the future.Inside an MCM the circuit components are mounted on the top layer. Other layers are used for pin redistribution and routing. As many layers are usually available for MCM routing, the main objective is to improve performance, i.e. to achieve tight packaging with lover fabrication cost, satisfying the constraints on net length, net separation, via size, via separation etc. Thus the primary goal is to minimize the number of vias, wire length, cross talks, delay in signal propagation, with the secondary objective of reducing the number of routing layers in the MCM.Several approaches to MCM routing have been proposed recently [4). A pair of routing layers called the layer-pair is considered at a time and yet unrouted terminals are projected on them though stack vias. Khoo and Cong developed SLICE (2] and VAR [3]. In the latter method at most four vias are used for routing two terminal net in a non-monotone fashion. Multi-terminal nets are transformed into two-terminal nets. Another algorithm, called SEGRA, was proposed in (1). It uses a plane sweep technique and splits each multi terminal net into two-terminal nets considering a minimum spanning tree among its terminals. ng its terminals.This algorithm outlines a new approach to MCM routing in Manhattan- diagonal model, that combines the advantage of both diagonal model and Manhattan geometry. Here two routing layers with fixed terminals in the Manhattan diagonal (+45) model has been considered. Thus, the wire segments may either be rectilinear or at +45° directions. The diagonal model is well supported by the fabrication process and provides better utilization of routing space, tends to reduce wire length and hence area and delay. However the existing algorithms based on the model are either too elementary or inefficient and therefore have limited capability to real life routing problems.Non-overlap model is considered in this routing algorithm. In non- overlap model generally those algorithms, which assume only vertical and horizontal wire segments, put all the non-overlapping vertical segments in a layer and all non-overlapping horizontal wire segments in the other layer of a layer-pair. But in this model, all the non-overlapping horizontal wire segments with some +45° bend are put in a layer and non-overlapping vertical wire segments with some +45° bends are put in the other layer of the layer pair.


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Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.


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