The integration of lab-scale bottom-up fabrication techniques and production-scale top-down methods can overcome current limits in nanofabrication[A1] . Selective deposition via atomic layer deposition (ALD) is a leading approach for such integration. We propose a gradient area-selective deposition (ASD) method to overcome the inherent limitation of nanofabrication of 3D nanostructures and demonstrate the applicability of the proposed method toward large-scale production of materials on the basis of theoretical calculations and simulations of molecular level interactions. Cp(CH₃)₅Ti(OMe)₃ (TMPMCT) is used as a molecular surface inhibitor to prevent the growth of ALD-treated TiO₂ films. TMPMCT adsorption was controlled gradually in a 3D nanoscale hole to achieve gradient TiO₂ growth. This resulted in the formation of perfectly seamless TiO₂ films with a high-aspect-ratio hole structure. This study also demonstrated that application of an additional H₂O pulse can improve the coverage and blocking property of the TMPMCT inhibitor. The experimental results were consistent with theoretical calculations based on density functional theory, Monte Carlo simulation, and the Johnson-Mehl-Avrami-Kolmogorov model. The gradient-ASD-treated TiO₂ film formation is based on the fundamentals of molecular chemical and physical behaviours, and the proposed method can be applied to the development of other material systems through ALD.