High density plasma reactive ion etching of magnetic tunnel junction (MTJ) stack was performed in an inductively coupled plasma. The etch process of MTJ stack masked with the photoresist and electron beam resist was studied using Ar, Cl2, BCl3 and O2 gas mixes and characterized in terms of etch profile and electrical properties. When MTJ stack was first etched down to CoFe free layer and the rest of MTJ stack was etched, the etch slope of MTJ stack was more vertical than MTJ stack etched by other methods. As Cl2 concentration and process pressure increased and coil rf power and dc bias decreased, the electrical properties of MTJ stack were improved. BCl3/Ar and Cl2/Ar gases were more effective in obtaining steep slope of the etched MTJ stack than the any other gas. By using high density plasma etching of MTJ stack, steep etch slope and clean etch profile without redeposition could be obtained.