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Elimination of Surface Conductivity of Polyimide

IP.com Disclosure Number: IPCOM000037930D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Ho, PS: AUTHOR

Abstract

In metal-ceramic polymer structures of the type used for packaging, via holes are produced by Ar ion-beam etching. However, this process can cause resputtering of metal atoms to the surface of the polymer (polyimide) layer and the formation of a carbon-rich layer on the surface of the polymer. This causes the polymer surface to become conducting, thereby destroying the desired insulating properties of the polyimide. Two methods are described to remove this surface conductive layer.

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Elimination of Surface Conductivity of Polyimide

In metal-ceramic polymer structures of the type used for packaging, via holes are produced by Ar ion-beam etching. However, this process can cause resputtering of metal atoms to the surface of the polymer (polyimide) layer and the formation of a carbon-rich layer on the surface of the polymer. This causes the polymer surface to become conducting, thereby destroying the desired insulating properties of the polyimide. Two methods are described to remove this surface conductive layer.

The first method uses low-power nitrogen or oxygen sputtering following the high-power Ar etching step, while the second method uses heating the structure in a N2O or H2O partial pressure atmosphere. The first method is intended to remove the surface metallic contamination as well as to restore the polyimide surface chemistry after Ar etching. A low-power beam, i.e. 500 to 1000eV, and low intensity is suitable for that purpose.

The second method is used for oxidizing the surface metallic and carbon contaminations; the former is mainly Cr and Cu. A partial pressure of about 10-5 torr and a temperature range of 150o to 450oC are suitable.

Disclosed anonymously.

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