Atomic Layer Deposition of Ta–N-Based Thin Films Using a Tantalum Source

Abstract

Ta–N-based thin films were deposited by thermal atomic layer deposition. In this work, we introduced a tantalum source. The alternate supply of this halide but liquid precursor tantalum pentachloride, diethyl sulfide (TPDS), and ammonia (NH3) resulted in Ta–N-based films with a saturated growth rate of approximately 0.2–0.3 Å/cycle at 300–400°C and less than 1 atom % chlorine. By pulsing trimethylaluminium (TMA) as an additional reacting agent between the TPDS and NH3 , the resistivity was improved up to 103μΩcm . These films showed a chlorine content of 10 atom % and an aluminum content of less than 1 atom %. X-ray photoelectron spectroscopy, X-ray diffraction, and a standard four-point probe method indicated a shift from tantalum nitride to tantalum-carbonitride-based films with increasing TMA and decreasing NH3 pulse numbers.

Atomic Layer Deposition of Amorphous Niobium Carbide-Based Thin Film Superconductors

“…TMA is widely used as a precursor in aluminum oxide (Al 2 O 3 ) ALD. However, TMA can also function as a reducing agent in the ALD of metal nitrides using halide precursors and ammonia. − ALD of both Ti(Al)N and Ta(Al)N , have been previously reported using TMA together with ammonia and metal chloride-based precursors. In a 2007 patent Härkönen and co-workers described an ALD-like process for depositing transition metal and carbon-containing films using metal halides (e.g., TiCl 4 ) and an organometallic carbon source (TMA) at temperatures between 250 and 550 °C .…”

Growth of the Initial Atomic Layers of Ta‐N Films During Atomic Layer Deposition on Silicon‐Based Substrates

“…A major concern of volatile Ta V precursors is the deposition of conductive Ta III N rather than low‐conducting Ta 3 N 5 films 7. Promising results were obtained for plasma‐assisted thermal ALD utilizing halide precursors such as TaCl 5 and TaF 5 7–11. In order to avoid issues associated with halides, to lower the deposition temperature, and to enhance nitride formation, research has focused on amido‐imido metal‐organic precursors, but often with modest results in electrical conductivity and film purity 12–16.…”