Determination of film thicknesses through the breakup of H2+ ions

The ever-growing demand of the semiconductor industry for smaller and faster chips is pressing for new developments on the characterization of ultra-thin films. In particular, ion scattering techniques are largely used to profile thin films and, as a general rule, the depth scale is given in atoms/cm2. We explore a new method to determine absolute thicknesses of ultra-thin amorphous films. This technique is based on the measurement of the dwell time of hydrogen fragments traversing amorphous films under the quasi-Coulomb explosion. High energy-resolution backscattering experiments were performed with incident H+ and H2+ ions interacting with ultra-thin films like LaAlO3, HfO2 and LaScO3. The experimental results are corroborated by transmission electron microscopy (TEM) measurements and show the effectiveness of the proposed technique.