Fluorine-containing polymeric inhibitor for highly selective and durable area-selective atomic layer deposition

Abstract

Area-selective deposition (ASD) is an emerging technique in the semiconductor industry with a downscaling feature size, as it generally allows a reduction of the number of process steps, improves cost-efficiency and placement accuracy, but remains compatible with CMOS processes. Among various ASD technics, area-selective atomic layer deposition (AS-ALD) with polymeric inhibitors has the advantage of being able to easily manipulate surface chemistry. We propose the AS-ALD of ZnO using a poly(2,2,2-trifluoroethyl methacrylate) (PTFEMA), which shows superior deposition suppression on the surface based on its hydrophobicity. Fluorine is essentially inert to diethyl zinc and H2O, and sufficient thermal stability helps to maximize the nucleation delay of ZnO. We achieved almost perfect selectivity of ZnO AS-ALD between SiO2 and PTFEMA, and the selectivity was highly durable regardless of severe depositing conditions. In addition, the performance was also demonstrated with Cu3N, proving the versatility of the inhibitor for utilizing conventional reactants (H2O and NH3). We fabricated the ZnO field effect transistors as proof-of-concept devices using a polymeric inhibitor and AS-ALD achieving a modest switching property (on/off current ratio > 106). Simple formation and removal of chemical contrast will provide an effective route for employing AS-ALD process to address challenges in recent device fabrication.