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Anodization Process for Planarization of Aluminum Copper Silicon Metallurgy

IP.com Disclosure Number: IPCOM000079750D
Original Publication Date: 1973-Aug-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 57K

Publishing Venue

IBM

Related People

Lhote, G: AUTHOR

Abstract

Conductive pathways for integrated circuit interconnections are formed and electrically insulated by blanket deposition of metallurgy, based on aluminum which is selectively converted into Al(2)O(3) by anodization. Planarity of the resulting circuit and insulation structure is achieved, by the controlled removal of a portion of the metallurgy to be anodized so that, subsequent to anodization, the unanodized and the anodized regions of the metallurgy are substantially coplanar.

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Anodization Process for Planarization of Aluminum Copper Silicon Metallurgy

Conductive pathways for integrated circuit interconnections are formed and electrically insulated by blanket deposition of metallurgy, based on aluminum which is selectively converted into Al(2)O(3) by anodization. Planarity of the resulting circuit and insulation structure is achieved, by the controlled removal of a portion of the metallurgy to be anodized so that, subsequent to anodization, the unanodized and the anodized regions of the metallurgy are substantially coplanar.

Referring to the figures, successive layers of aluminum-copper, silicon and aluminum are deposited on the semiconductor substrate, as shown in Fig. 1. A thin barrier layer is formed on the top of the aluminum layer by anodizing the aluminum to a thickness of about 800 Angstroms to 1,000 Angstroms, as in Fig.
2. The desired metal pattern is defined by photoetching the unprotected barrier layer, as shown in Fig. 3. The exposed aluminum then is anodized fully down to the silicon layer, as in Fig. 4. The completion of the aluminum anodization is indicated by an observable shift of the anodization parameters (voltage and current), which occurs when the anodization reaches the silicon layer.

The porous aluminum oxide resulting from the last anodization step is etched away along with the thin silicon layer, as shown in Fig. 5. The removed fully anodized aluminum layer provides space for the growth of anodized aluminum- cop...