Process-Decoupled Integration of Functional Polymer Dielectrics via Metal–Polymer Direct Bonding

Functional polymers offer attractive dielectric, mechanical, and electrical properties for heterogeneous semiconductor systems, but their direct introduction into conventional semiconductor process flows can be restricted by concerns regarding organic contamination, residue formation, outgassing, and incompatibility with subsequent processing. In this work, we demonstrate a bonding-enabled, process-decoupled integration strategy in which a functional polymer is fabricated separately and subsequently incorporated into a semiconductor-compatible structure through plasma-activated direct bonding between a Ti surface and poly(1,3,5-trimethyl-1,3,5-trivinylcyclotrisiloxane) (pV3D3). Unlike conventional hybrid-bonding schemes that require separately prepared metal–metal and dielectric–dielectric interfaces, the proposed architecture uses pV3D3 itself as both the functional dielectric and a bonding constituent, thereby eliminating polymer-side dielectric patterning and subsequent metallization. Atomic force microscopy (AFM) confirmed that plasma treatment preserved the subnanometer surface roughness of pV3D3, while X-ray photoelectron spectroscopy (XPS) revealed that O2 plasma introduced oxygen-containing functional groups, without pronounced morphological degradation. Scanning acoustic tomography (SAT) and shear testing showed that O2 plasma activation enhanced the metal–polymer bonding strength. Within the investigated process-window screening, the highest measured shear strength was obtained after 200 W O2 plasma treatment and thermal compression bonding at 250 °C for 3 h. Cross-sectional transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS) confirmed local interfacial continuity and preservation of the designed Ti/pV3D3 heterogeneous stack. Finally, the bonded structures retained repeatable SET-like transitions and statistically distinguishable current states, showing that the plasma-activation and thermal-compression-bonding sequence did not eliminate the characteristic electrical response of pV3D3. These results establish direct Ti–polymer bonding as a process-decoupled route for integrating a functional polymer while reducing auxiliary bonding layers and preserving mechanical integrity and postbond electrical operability.