About cookies on this site Our websites require some cookies to function properly (required). In addition, other cookies may be used with your consent to analyze site usage, improve the user experience and for advertising. For more information, please review your options. By visiting our website, you agree to our processing of information as described in IBM’sprivacy statement. To provide a smooth navigation, your cookie preferences will be shared across the IBM web domains listed here.
Publication
ECS Meeting 2006
Conference paper
A novel, selective, freelayer wet etching method for magnetic tunnel junction-based MRAM
Abstract
This paper describes the development of a novel wet etch process for selective patterning of ferromagnetic freelayers, principally Permalloy, m MRAM magnetic tunnel junction (MTJ) stacks. The method uses a nonadsorbing acid, trifluoromethane sulfonic (TFMSA), as the etchant acid. Freelayer etch selectivity to the alumina tunneling barrier is achieved through the use of long-chain alkane sulfonic acid salts, eg. sodium 1-tetradecanesulfonate. These inhibitors can increase the alumina barrier etch resistance in the TFMSA solution by up to two orders of magnitude. The importance of the reactive ion etching process used for MTJ cap layer removal prior to the wet etching step is discussed. Open circuit potential (OCP) was shown to be a powerful method for following the progress of freelayer wet etching and for evaluating alumina barrier etch inhibitors. copyright The Electrochemical Society.