Etch characteristics of magnetic tunnel junction stack using a high density plasma in a HBr/Ar gas

Abstract

Etch characteristics of magnetic tunnel junction (MTJ) stack masked with TiN thin films were investigated using an inductively coupled plasma reactive ion etching in HBr/Ar gas for the application of magnetic random access memory. The effect of HBr gas concentration on the etch profile of MTJ stacks was examined. As HBr gas concentration increased, the sidewall angles of etched patterns of MTJ stacks were slightly improved. The effect of etch parameters including coil rf power, dc-bias voltage, and gas pressure on the etch profile of MTJ stack was explored. At low coil rf power, low dc-bias voltage, and high gas pressure, the etching of MTJ stack displayed better etch profile. A high degree of anisotropic etching of MTJ stacks without redeposition was achieved using HBr/Ar gas at the optimized etch conditions. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA,.