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Monitoring Structure for Trench Dislocations

IP.com Disclosure Number: IPCOM000036593D
Original Publication Date: 1989-Oct-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Plougonven, C: AUTHOR

Abstract

Dislocations are often generated at the vicinity of polysilicon-filled trenches. The analysis of these dislocations, because of their small density, requires fast and accurate localization.

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Monitoring Structure for Trench Dislocations

Dislocations are often generated at the vicinity of polysilicon-filled trenches. The analysis of these dislocations, because of their small density, requires fast and accurate localization.

In a standard process sequence, a large number of transistors are interconnected with metallurgy for electrical probing and defect detection.

A process sequence involving polysilicon deposition that allows interconnection of trench-isolated pedestals is described hereafter. An electrical testing of the subcollector-to-base junction with the polysilicon contacts allows early defect detection and analysis.

According to this process sequence, polybase contacts are opened after trench formation and filling. Then the polysilicon is deposited, oxidized and ion implanted. Ion implantation is followed by a drive-in. A special test structure mask is used to generate stripes of polysilicon ending in testing pads. The oxide is then etched off in a plasma etcher. The structure is then ready for electrical testing.

The breakdown voltage between the polysilicon filled trenches and polysilicon base is measured for leakages. Furthermore, the polybase stripe pattern allows for cutting the stripes in order to localize the defects to permit failure analysis.

The main advantage of this polysilicon wiring of a test structure to detect junction leakage is a significant reduction of time between trench formation and test. As a result, quicker evaluation o...