Abstract: A method for optimal placement of cells on a surface of an integrated circuit, comprising the steps of comparing a placement of cells to predetermined cost criteria and moving cells to alternate locations on the surface if necessary to satisfy the cost criteria. The cost criteria include a timing criterion based upon interconnect delay, where interconnect delay is modeled as a RC tree expressed as a function of pin-to-pin distance. The method accounts for driver to sink interconnect delay at the placement level, a novel aspect resulting from use of the RC tree model, which maximally utilizes available net information to produce an optimal timing estimate. Preferred versions utilize a RC tree interconnect delay model that is consistent with timing models used at design levels above placement, such as synthesis, and below placement, such as routing. Additionally, preferred versions can utilize either a constructive placement or iterative improvement placement method.

Abstract: Tile-based routing between a bump pad and an input/output (I/O) device for implementation on a flip-chip integrated circuit (IC) die. A trace is routed between the bump pad and a position corresponding to a first I/O slot, the first I/O slot being at least partially occupied by the I/O device. A position is obtained for a device pad for the I/O device. The trace is then extended into an area corresponding to the position obtained for the device pad. It is a feature of this aspect of the invention that the trace extension extends the trace into a pad area for a second I/O slot, the second I/O slot being at least partially occupied by the I/O device. The invention also concerns a flip-chip integrated circuit (IC) die that includes a bump pad, an input/output (I/O) device, and a device pad electrically connected to the I/O device and disposed vertically adjacent to a portion of the I/O device.

Abstract: The present invention is a method for searching an identity base for identities that can be applied to a given formula. The method includes transforming the formulas from an identity base into a standard form, creating a set of code words for said identity base, constructing a lexicographical tree of a code word set of said identity base, and outputting a list of formula numbers from said identity base.

Abstract: The present invention is a method and apparatus for applying proximity correction to a piece of a mask pattern, by segmenting the piece into a plurality of segments, and applying proximity correction to a first segment without taking into consideration the other segments of the piece.

Abstract: A method for routing nets in an integrated circuit design, said method comprising the steps of dividing the integrated circuit design with lines in a first direction and lines in a second direction, forming a routing graph having vertices and edges, wherein vertices correspond to locations where lines in the first direction cross lines in the second direction, routing nets as a function of said routing graph with parallel processors operating substantially simultaneously, determining the relative wire congestion among different areas in the integrated circuit design, and rerouting nets passing though areas with a relatively high wire congestion.

Abstract: A method for routing a net on an integrated circuit device, said method comprising the steps of creating a list of basis elements of the net, said basis elements being defined by a predetermined size limitation, determining a complexity value for each basis element as a function of the distance between pins in the basis element, forming a hypertree for the net as a function of complexity values of basis elements so determined, and routing the net as a function of the hypertree.

Abstract: A system for optimizing placement of cells a surface of a semiconductor chip divided into regions is provided herein. The system repetitively calculates affinities for relocating cells to alternate regions, repositioning cells having a maximum affinity greater than a predetermined threshold to the region providing the maximum affinity for the cell based on an influence parameter. The system then alters the influence parameter and repeats the previous functions for a predetermined number of times.

Abstract: Integrated circuit chips (IC's) require proper placement of many cells (groups of circuit components) and complex routing of wires to connect the pins of the cells. Because of the large number of the cells and the complex connections required, it is essential that wire routine be done correctly to avoid any congestion of wires. Placement of the cells and the routing of the wires to avoid congestion can be accomplished by determining congestion of various regions of the IC's after an initial placement of the cells and routing of the wires. The present invention discloses a method and apparatus to determine the congestion of the regions and a technique to increase the fictive heights (or, the "working height", or the "working size") of the cells for repeating the placement of the cells if the current placement and routing leads to congestion. The present invention provides for a method of defining regions and line segment.

Abstract: An initial placement of cells for an integrated circuit chip is decomposed into a hierarchial order of groups of cells. The groups are routed simultaneously using parallel processors, and the results are recomposed to provide a global routing that provides a detailed mapping of cell interconnect congestion in the placement. Areas of high congestion are identified, and a congestion reduction algorithm is applied using the parallel processors to alter the placement in these areas simultaneously. The overall fitness of the placement is then computed, and if it has not attained a predetermined value, the steps of identifying congested areas and applying the congestion reduction algorithm to these areas are repeated. The cumulative error created by altering the placement without repeating the global routing is estimated, and if it exceeds a predetermined value, the global routing is also repeated.