Etchant-Free Wafer-Scale 2D Transfer and van der Waals 3D Integration via Peel-Off Force Engineering.

Abstract

Clean van der Waals (vdW) contacts are critical for realizing high-performance, reliable devices and integrated circuits based on two-dimensional (2D) transition metal dichalcogenides (TMDs). However, conventional transfer methods that rely on etchants often degrade TMDs, hampering the formation of pristine vdW interfaces. Here, we suggest an etchant-free transfer technique that prevents both direct and indirect damage by precisely controlling the peel-off force (POF) through surface-tension modulation (STM). Guided by a modified Kendall's model, we determine the optimal surface tension for common, nontoxic mixtures of deionized water and ethanol, thereby maximizing the POF. Using this POF-assisted method, we fabricate high-performance 2D vdW field-effect transistors (FETs), integrating device components without etchant-induced damage. These FETs exhibit a field-effect mobility of 162.2 cm² ·V^-1 ·s^-1, an on/off ratio exceeding 10⁸, a subthreshold swing of 72 mV·dec^-1, and an interface trap density of ∼10¹² cm^-2·eV^-1, demonstrating high-quality vdW contacts. Finally, we suggest the all-vdW logic circuit design, demonstrated through a complementary metal-oxide-semiconductor (CMOS) logic test structure. This work demonstrates a process-compatible approach for the lab-to-fab transition of 2D TMD electronics, achieving reliable device yields and the performance levels required for next-generation vdW-integrated systems.