Low-Resistivity Titanium Nitride Thin Films Fabricated by Atomic Layer Deposition with TiCl₄ and Metal–Organic Precursors in Horizontal Vias

Abstract

The resistivity of halogen-free atomic layer deposition (ALD) TiN thin films was decreased to 220 μΩ cm by combining the use of a high-thermal stability nonhalogenated Ti precursor with a highly reactive nitrogen source, anhydrous hydrazine (N 2 H 4 ). TDMAT [tetrakis (dimethyl-amino)titanium], TDEAT [tetrakis(diethylamido)titanium], and TEMATi [tetrakis (ethylmethyl-amido)titanium] were compared to TiCl 4 as precursors for ALD TiN using N 2 H 4 as a coreactant. By minimizing the pulse length of the Ti-source precursor and optimizing the deposition temperature, the resistivity of TiN thin films deposited using these precursors was reduced to 400 μΩ cm for TDMAT (at 350 °C), 300 μΩ cm TDEAT (at 400 °C), and 220 μΩ cm for TEMATi (at 425 °C) compared to 80 μΩ cm for TiCl 4 (at 500 °C). The data are consistent with the lowest resistivity for halogen-free ALD corresponding to the organic precursor with the highest thermal stability, thereby allowing maximum ALD temperature. After optimization, TiN thin films were grown in horizontal vias, illustrating conformal and uniform TiN using both TiCl 4 and TEMATi in horizontal vias in patterned substrates.

Low sheet resistance buried metal bit line realized by high-temperature metal CVD process in vertical channel transistor array

“…When measuring the electrical characteristics of BBL structures, it is imperative to take into account the film thickness, dimensions of individual material layers, and their respective electrical resistivities. Specifically, in the case under consideration, the resistivity of TiN is approximately 2.2 × 10 −6 Ω•m, 30) the resistivity of lowresistivity TiSi x is approximately 5 × 10 −7 Ω•m, 30) and the resistivity of W stands at approximately 1.6 × 10 −7 Ω•m. 30) It becomes evident that the resistance characteristics of the BBL are predominantly governed by the relatively high resistivity of TiN.…”

“…Specifically, in the case under consideration, the resistivity of TiN is approximately 2.2 × 10 −6 Ω•m, 30) the resistivity of lowresistivity TiSi x is approximately 5 × 10 −7 Ω•m, 30) and the resistivity of W stands at approximately 1.6 × 10 −7 Ω•m. 30) It becomes evident that the resistance characteristics of the BBL are predominantly governed by the relatively high resistivity of TiN. From this perspective, in order to further reduce the resistance of the bit lines, it is also necessary to open the bottom of the silicon column and adopt the strategy of using W metal- 04SP68-3 © 2024 The Japan Society of Applied Physics filled conductive lines, as shown in Fig.…”