MTJ stack and bottom electrode patterning process with ion beam etching using a single mask

US9166154B2 · kind B2 · utility

Assignee

• Avalanche Technology, Inc. · US

Inventors

• Kimihiro Satoh · Wilsonville, US
• Dong Ha Jung · Pleasanton, US
• Jing Zhang · Los Altos, US
• Benjamin Chen · San Jose, US
• Yiming Huai · Pleasanton, US
• Rajiv Yadav Ranjan · San Jose, US
• Yuchen Zhou · San Jose, US

Key dates

• Filing date: Dec 4, 2013
• Grant date: Oct 20, 2015
• Expiry date: Dec 4, 2033

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10N50/01

Abstract

Fabrication methods using Ion Beam Etching (IBE) for MRAM cell memory elements are described. In embodiments of the invention the top electrode and MTJ main body are etched with one mask using reactive etching such as RIE or magnetized inductively coupled plasma (MICP) for improved selectivity, then the bottom electrode is etched using IBE as specified in various alternative embodiments which include selection of incident angles, wafer rotational rate profiles and optional passivation layer deposited prior to the IBE. The IBE according to the invention etches the bottom electrode without the need for an additional mask by using the layer stack created by the first etching phase as the mask. This makes the bottom electrode self-aligned to MTJ. The IBE also achieves MTJ sidewall cleaning without the need for an additional step.