Paper TF2-TuM6
Effects of Halogenated Plasma Chemistries on Degradation of Magnetic Material Properties

Tuesday, October 19, 2010, 9:40 am, Room Ruidoso

Patterning of magnetic materials with plasma processes is an integral step in the fabrication of magnetic devices such as magnetic tunnel junctions (MTJs) for magnetoresistive random access memory (MRAM). Obtaining optimal device performance requires preservation of the magnetic material properties throughout the fabrication process, and thus places limitations on the process window (e.g. temperature, gas chemistry) for patterning devices. Due to this, the use of halogenated plasma chemistries, which are commonly used in reactive ion etching (RIE) processing, must be carefully employed when patterning MTJ devices, as they can significantly degrade magnetic properties during the etch. One method used to minimize magnetic degredation is the incorporation of metallic capping layers which potentially isolate the halogen etch chemistry from the critical magnetic layers. However, the optimal thickness and/or properties of these layers have yet to be fully explored. For example, when a Cl₂ based plasma is exposed to a 300 Å Ru capping layer, the magnetic moment/area of the underlying magnetic free layer is reduced 11% from 1.64 to 1.46×10^-4 emu/cm². Therefore in this work, the effects of the plasma etch chemistry on magnetic materials is explored using various halogenated chemistries and capping layer materials to understand the mechanisms by which patterning of magnetic devices can be achieved without degradation of magnetic properties.