Atomic Layer Deposition of Ta(Al)N(C) Thin Films Using Trimethylaluminum as a Reducing Agent

Abstract

Ta͑Al͒N͑C͒ thin films were deposited by the atomic layer deposition technique using TaCl 5 or TaBr 5 and NH 3 as precursors and Al͑CH 3) 3 as an additional reducing agent. For comparison TaN thin films were deposited also from TaBr 5 and NH 3 with and without Zn. The films were analyzed by means of the time-of-flight elastic recoil detection analysis, energy dispersive X-ray spectroscopy, X-ray diffraction, and standard four-point probe method. The deposition temperature was varied between 250 and 400°C. The films contained aluminum, carbon, hydrogen, and chlorine impurities. The chlorine content decreased drastically as the deposition temperature was increased. The film deposited at 400°C contained less than 4 atom % chlorine and also had the lowest resistivity, 1300 ⍀ cm. The barrier properties of the Cu/Ta͑Al͒N͑C͒/Si structure were studied by using sheet resistance and X-ray diffraction measurements.

Plasma-Assisted Atomic Layer Deposition: Basics, Opportunities, and Challenges

“…329 Cubic TaN, can be deposited by thermal ALD when N 2 H 4 is used as the reactant 330 or with the help of additional reducing agents such as AlMe 3 or elemental Zn. 329,331 However, these processes employ relatively uncommon reactant gases or additional reducing agent dosing steps, which add significantly more complexity to the deposition process. For plasma ALD processes, it is possible to deposit conductive cubic TaN films from metal-organic precursors using an H 2 plasma.…”

Atomic layer deposition of TaN and Ta3N5 using pentakis(dimethylamino)tantalum and either ammonia or monomethylhydrazine

“…The halide precursors including TaF 5 [31], TaCl 5 [13,32], and TaBr 5 [33] have been most widely studied, however, these tend to form corrosive hydrogen halide by-products, which can damage deposition equipments. Halide precursors also require relatively high deposition temperatures (4400 1C) to prevent halide contamination of the films [32].…”

“…Ammonia is the most widely used nitrogen co-reactant in thermal ALD of nitrides, however, previous studies have only been able to obtain nitrogen rich Ta 3 N 5 when ammonia was used with either tantalum halide [32] or amide [39] precursors. Reductants such as zinc [32] and trimethylaluminium (TMA) [33] have been used with ammonia to produce conductive TaN, however, transport of zinc vapour requires high temperatures ( 4400 1C) and the use of TMA results in both Al (12 at%) and C (22 at%) impurities. Hydrazines are another class of nitrogen co-reactants that can be used for nitride ALD and offer superior reactivity to ammonia [40].…”

Effects of thermal treatment on structures of Cu/atomic-layer-deposited TaN films/Si stacks

“…TaN x films have been found promising as thin film resistors [1] and diffusion barriers [2][3][4] in ultra-large scale integrated circuits, as well as mask layers for X-ray lithography [5]. Several procedures were reported to obtain ALD TaN films, and their structures and properties were also characterized by means of X-ray diffraction (XRD) and transmission electronic microscopy (TEM) [6][7][8][9].…”

“…Generally, O, C and H are the main impurities in such ultrathin films because they are prepared using metallorganic precursors and reducers [6][7][8][9][10][11]. These impurities change the structures and properties of the TaN films [6][7][8][9]. Obviously, a study of the impurities effects is an important part of the study of the thermal behavior and barrier properties of Cu/TaN/Si stacks.…”