Browse Prior Art Database

On-Chip Electrical Monitor for Critical Mask Alignment

IP.com Disclosure Number: IPCOM000061530D
Original Publication Date: 1986-Aug-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Chesebro, DG: AUTHOR [+2]

Abstract

An electrical monitor, consisting of a metal line which overlays portions of an isolation groove, is used to detect misalignment of critical masks. The monitor provides a means to screen product at final test for potential reliability problems related to sensitive device structures. The application of the monitor, as described in this article, is for testing metal line integrity over a trench isolation structure. As shown in Fig. 1, the monitor consists of a minimum width metal line passing over a polyimide-filled isolation groove in both the X and Y directions. The monitor may be repeated many times on a given integrated circuit IC chip. Both ends of the metal lines are brought out to external terminals and tested at final test.

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On-Chip Electrical Monitor for Critical Mask Alignment

An electrical monitor, consisting of a metal line which overlays portions of an isolation groove, is used to detect misalignment of critical masks. The monitor provides a means to screen product at final test for potential reliability problems related to sensitive device structures. The application of the monitor, as described in this article, is for testing metal line integrity over a trench isolation structure. As shown in Fig. 1, the monitor consists of a minimum width metal line passing over a polyimide-filled isolation groove in both the X and Y directions. The monitor may be repeated many times on a given integrated circuit IC chip. Both ends of the metal lines are brought out to external terminals and tested at final test. If a given critical mask such as the block mask used to etch the polyimide is misaligned further than allowed in the design ground rules, an etched hole will exist in the sidewall D of the polyimide- filled groove (Fig. 2). When metal is deposited on this typography, it forms a thin and weak metal line over the etched polyimide hole. This metal may contact the silicon, as shown at C of Fig. 2, through the etched side wall D. The areas of concern are identified as A and B in Figs. 1 and 2. If the metal is shorted to the silicon, the chip is rejected. An integrity check of the metal line may be made by the application of a high current to the monitor. If the metal structure is thin and...