Magnetron sputtering method was utilized at room temperatures to deposit silicon oxide (SiO2), which was thermally oxidized. The substrate structure was a composition of Silicon (Si), SiO2, iron, and copper element with boron (CoFeB), Magnesium oxide (MgO), Tantalum (Ta) and Ruthenium (Ru). The first ferromagnetic material constituting CoFeB was then deposited, followed by deposition of MgO layers. The pressure used in MgO deposition was ten mTorr in the Ar atmosphere. Following this, MTJ sensor samples were then annealed successively at a temperature of 5000C for one hour, under a strong 400 mT magnetic field.
Further, cross-sections of the MTJ sensor were cut, grounded and dimpled to miniature specimens of about 20nm. Subsequently, an argon ion-beam thinning process followed, and radiation damage was reduced by utilizing an incident beam incident at 4-60. The stated process helped in imaging observation in TEM and STEM. A conventional microscope was also utilized to take images for analysis. The specific images taken for both TEM and STEM were HRTEM and ABF STEM, respectively.