Defect Free Pattern Definition of AlCu Films
Original Publication Date: 1981-Sep-01
Included in the Prior Art Database: 2005-Feb-12
Defect-free aluminum-copper conductor patterns for use in bubble memories are formed by including the processing step of presoaking the garnet wafers in an acid, such as acetic acid (50 ml/1), after they have been exposed to a silicate containing photoresist developer and before they have been rinsed with water. The silicate acts as an inhibitor to attack by the alkaline developer. Other suitable acids are typically nitric acid (50 ml of 70%/1) and chromic acid (50 g/1). The key to forming a pit-free aluminum-copper pattern is to peptize the silicate of the developer so that it cannot, on dilution, form a gel which occludes alkali. This results in immediate neutralization of alkali before it can attack the AlCu surface.