New Wet Process Strategies for Reduced La 2 O 3 and MgO 2 High-k Cap-dielectric Loss

Lanthanum oxide (LaxOy) and magnesium oxide (MgxOy) high-k cap-dielectrics have been used to modulate the effective work function for high-k/metal gate CMOS devices. The use of DIW during wet processing leads to unacceptable material loss due to the high solubility of materials. In this work, new rinsing procedures with pH-controlled and solvent-based solutions were evaluated in order to avoid material loss. It is validated that both pH-controlled (> pH 10) and solvent-based solutions achieve less than 1 Aå of La2O3 loss and solvent-based solutions can well be used on MgO2, providing less than 1 Aå loss. Furthermore, no adverse affects, such as an increase in particle or surface roughness, were observed by applying the new rinsing procedures.