Browse Prior Art Database

Method for Identifying Donut-Shaped Metal Wiring in VLSI Graphic Data

IP.com Disclosure Number: IPCOM000035812D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Downey, JH: AUTHOR

Abstract

In the back end of a semiconductor processing line, metal wiring is often deposited using a lift-off process. The removal of the metal can not be guaranteed for a donut-shaped metal line. These donut-shapes must be flagged before the mask design is submitted to manufacturing so that the integrity of the design is not compromised. The previous method of flagging these donut-shapes is to first union the metal level and then check the resulting shapes for inside topologies, as shown in Fig. 1. The inside topologies are then brought to the layout person's attention so that the design may be corrected. The following problems could cause the layout to be uncheckable for donut-shaped wiring: 1. In order for shapes to be unionized, the layout data must be unnested. Unnesting of layout data can generate large amounts of "flattened" data.

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Method for Identifying Donut-Shaped Metal Wiring in VLSI Graphic Data

In the back end of a semiconductor processing line, metal wiring is often deposited using a lift-off process. The removal of the metal can not be guaranteed for a donut-shaped metal line. These donut-shapes must be flagged before the mask design is submitted to manufacturing so that the integrity of the design is not compromised. The previous method of flagging these donut-shapes is to first union the metal level and then check the resulting shapes for inside topologies, as shown in Fig. 1. The inside topologies are then brought to the layout person's attention so that the design may be corrected. The following problems could cause the layout to be uncheckable for donut-shaped wiring: 1. In order for shapes to be unionized, the layout data must be unnested. Unnesting of layout data can generate large amounts of "flattened" data. The data volume is so large that the job may result in an abnormal end (ABEND). 2. The CPU time needed to unnest the layout, union the "flattened" data and operate on this data could approach the mean-time to failure of the computer. 3. If the layout person needs to retain the unnested data, then that person is forced to manage a "flattened" layout. This is completely unreasonable with current VLSI technology.

An algorithm which can check donut-shaped metal wiring is shown. The algorithm can be used on nested or unnested data so that excessive CPU time and large data vo...