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Pretreatment of Lower Metallurgy to Increase Etch Rate of Passivating Materials

IP.com Disclosure Number: IPCOM000093061D
Original Publication Date: 1967-Apr-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Kaplan, LH: AUTHOR [+2]

Abstract

This technique minimizes etching time to prevent the formation of short circuits between insulation spaced conductors as a result of etching through flaws in a photoresist. The technique is for the pretreatment of areas from which SiO(2) or other passivating material is to be removed to cause the SiO(2) over the pretreated areas to etch at a much faster rate over the untreated areas.

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Pretreatment of Lower Metallurgy to Increase Etch Rate of Passivating Materials

This technique minimizes etching time to prevent the formation of short circuits between insulation spaced conductors as a result of etching through flaws in a photoresist. The technique is for the pretreatment of areas from which SiO(2) or other passivating material is to be removed to cause the SiO(2) over the pretreated areas to etch at a much faster rate over the untreated areas.

The areas over which the etch rate of subsequently deposited SiO(2) is increased are pretreated by roughening these areas either physically or chemically. For example, after coating with a photoresist hole pattern, the exposed areas which can be aluminum can be electrolessly plated with copper to form a very rough surface. The photoresist is removed and SiO(2) is sputtered on the same surface. A second photoresist hole pattern is applied to the SiO(2) and it is etched. Due to the rough surface underneath the hole patterns, the SiO(2) etches at a higher rate in these areas, permitting a shortened etch time to achieve contact. The shortened etch time reduces the possibility of the etch penetrating through flaws in the SiO(2) and causing short circuits to occur through these flaws upon subsequent metallization. The presence of the copper layer provides the added advantage in that it acts as a barrier for the attack of hydrofluric acid on aluminum. Nitric acid which does not attack aluminum can be utilized to...