Specific Process Knowledge/Etch/IBE⁄IBSD Ionfab 300/IBE magnetic stack etch

Results of Design of Experiments optimization of magnetic stack etching

Process parameters for the acceptance test

To find the optimal parameters, Design of Experiments was applied, with the intervals shown on the figure below.

Parameter	Ti etch acceptance
Neutalizer current [mA]	450
RF Power [W]	800
Beam current [mA]	400
Beam voltage [V]	500
Beam accelerator voltage	500
Ar flow to neutralizer [sccm]	5.0
Ar flow to beam [sccm]	10.0
Rotation speed [rpm]	20
Stage angle [degrees]	5
Helium backside cooling [Torr]	37.5

DoE for MLS etch

Some SEM profile images of the etched stacks

Magnetic stack of Ta/MnIr/NiFe/Ta/Tao/Ta/MnIr/NiFe/Ta etched with the optimal parameters shown above. Redeposition of etched material at photo resist. Profile ~78°	Etched magnetic stack with poor structure transfer, the parameters chosen was clearly not optimal. Chosen etch parameters result in severe footing	Etched magnetic stack with poor structure transfer, the parameters chosen was clearly not optimal. Chosen etch parameters result in severe trenching

Endpoint detection with SIMS

The endpoint for etching is determined by the integrated SIMS

End point detection is achieved by SIMS, and the etch rate is approximately 25 Nm/min. Resist stripping can be hard due to burned resist, to remedy this try to lover the current. Changing the currect will chance the sidewall angle and new studies of etch profiles will be necessary. For help, discussion and further info please contact Kristian Hagsted Rasmussen.