MTJ STACK AND BOTTOM ELECTRODE PATTERNING PROCESS WITH ION BEAM ETCHING USING A SINGLE MASK

摘要

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.

主权项

1. A method of fabricating an array of memory cells on a wafer comprising:
depositing a stack of layers for the memory cells including top electrode layer, a set of layers for memory elements and a bottom electrode layer on the wafer; executing a first etching process to remove unmasked areas of at least the top electrode layer using a mask that defines the array of memory cells; and performing a second etching process using ion beam etching to remove exposed layers around the array of memory cells including the bottom electrode layer while rotating the wafer and to clean exposed sidewalls of the set of layers for the memory elements, and wherein at least a portion of the ion beam etching is performed at a selected ion beam incidence angle greater than zero degrees.