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Super-Adhesive Bonding of Metal to Polyimide

IP.com Disclosure Number: IPCOM000040667D
Original Publication Date: 1987-Dec-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Efros, AA: AUTHOR [+3]

Abstract

Polyimide is commonly used as a dielectric in various packaging products in which the adhesion of metal lines to the polyimide is critical. The process described gives improved adhesion for evaporated or sputtered chromium metallurgy. The process consists of RF sputter etching of the polyimide surface, preheating to 400oC and then in-situ sputter depositing successive layers of chromium (Cr), copper (Cu), and chromium (Cr). The argon pressure used in the sputter etching and sputter depositing is in the range 8-18 mTorr. The RF power density used in the sputter etching is 3-4 W/in2 . Typical sputter etching times have been 10 minutes. During sputter etching of polyimide, a very thin metallic layer (Cr) deposits on the polyimide surface.

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Super-Adhesive Bonding of Metal to Polyimide

Polyimide is commonly used as a dielectric in various packaging products in which the adhesion of metal lines to the polyimide is critical. The process described gives improved adhesion for evaporated or sputtered chromium metallurgy. The process consists of RF sputter etching of the polyimide surface, preheating to 400oC and then in-situ sputter depositing successive layers of chromium (Cr), copper (Cu), and chromium (Cr). The argon pressure used in the sputter etching and sputter depositing is in the range 8-18 mTorr. The RF power density used in the sputter etching is 3-4 W/in2 . Typical sputter etching times have been 10 minutes. During sputter etching of polyimide, a very thin metallic layer (Cr) deposits on the polyimide surface. This is caused by back-sputtering (redeposition) of the pallet material onto the polyimide surface. In this process, a Cr-coated pallet is used. The redeposition occurs simultaneously with the etching process on the polyimide surface. This mechanism is shown in Fig. 1. As the atoms are deposited, the loosely adhering atoms are ejected by the bombardment of the Ar+ ions whereas the tightly bound atoms remain on the surface. Thus, the simultaneous deposition and etching results in a film that is very tightly bound to the polyimide layer. This is then followed by sputter deposition of Cr-Cu-Cr metallurgy of desired thickness.

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The idea of simultaneous sputtering and etching m...