Low-temperature synthesis of two-dimensional (2D) transition metal dichalcogenides (TMDs) is a key challenge for their integration with complementary metal-oxide-semiconductor (CMOS) technology at 'back-end-of-line (BEOL)'. Most low-temperature synthesis utilizes alkali salts, oxide-based metals, and methyl-group based chalcogen precursors which do not meet current BEOL requirements for contaminant-free manufacturing and process scalability. In this study, we benchmark a carbon and alkali salt-free synthesis of fully coalesced, stoichiometric 2D WSe2 films on amorphous SiO2/Si substrates at BEOL- compatible temperatures (475 °C) via gas-source metal-organic chemical deposition. This work highlights the necessity of a Se-rich environment in a kinetically limited growth regime for successful integration of low-temperature 2D WSe2. Atomic-scale characterization reveals that BEOL WSe2 is polycrystalline with domain size of ∼200 nm and band gap of 1.8 eV. Back-gated and electrolyte double layer gated field-effect transistors (FETs) exhibit increased ON currents as high as 4 µA µm-1 and ON/OFF ratios of ∼106, demonstrating a 100× improvement compared to previously reported BEOL compatible TMDs.
|Original language||English (US)|
|State||Published - 2020|
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering