Transfer of Freestanding Fluoropolymer Films for Advanced Semiconductor Devices

TL;DR

This paper presents a novel transfer method for integrating high-quality, low-k fluoropolymer dielectric films onto various substrates, enabling improved electronic device performance without damaging sensitive interfaces.

Contribution

The study introduces a new transfer technique for freestanding fluoropolymer films, filling a gap for low-k dielectric integration in advanced electronics.

Findings

Transferred films exhibit high breakdown fields (~8 MV/cm).

Devices show high mobility (~400 cm²/Vs) and low interface trap density.

Leakage currents remain below 10^-7 A/cm² before breakdown.

Abstract

High-quality dielectric films are essential for fabricating advanced electronic devices, but their direct deposition often degrades the films and their underlying interfaces, which compromises device performance, especially on sensitive or low-adhesion surfaces. To overcome these limitations, film transfer methods enable the integration of high-quality dielectric films onto such surfaces without damaging the underlying interfaces. However, existing transfer methods have predominantly focused on high-dielectric-constant (high-$\kappa$) materials, leaving a critical gap for transferable, high-quality low-$\kappa$ alternatives, which are required for enabling low-power and high-speed electronics. Herein, we address this need by demonstrating a method to integrate freestanding low-$\kappa$ fluoropolymer dielectric films with smooth surface morphology onto diverse substrates, including low-adhesion surfaces like hydrogen-terminated diamond. The transferred films revealed high breakdown fields of ${8.0}\pm{1.2}$ MV cm$^{-1}$, with leakage current density remaining typically below ${10}^{-7}$ A cm$^{-2}$ before the breakdown. The incorporation of these fluoropolymer films as gate dielectrics in p-channel hydrogen-terminated diamond field-effect transistors resulted in transfer and output characteristics with negligible hysteresis, high channel mobility (${\approx}400$ cm$^{2}$V$^{-1}$s$^{-1}$) and a low interface trap density (${\le}3{\times}10^{11}$ cm$^{-2}$eV$^{-1}$). These findings highlight the versatility of the transfer method and position freestanding fluoropolymers as a promising platform for forming high-quality dielectric/semiconductor interfaces for advanced electronics.