A new TiN precursor, tetrakis(ethylmethylamido)titanium (TEMAT), has been developed and characterized in terms of volatility and stability under CVD process conditions. In addition, titanium nitride thin films were prepared by means of metal organic chemical vapor deposition (MOCVD) technique, using TEMAT as a precursor. Depositions on SiO2 patterned wafers were carried out at 250−350 °C and the pressure of 1 Torr, yielding growth rates from 50 to 1550 Å/min. Excellent bottom coverage of ∼90% over 0.35 μm contacts with an aspect ratio of 2.9 was achieved at 300 °C. This excellent bottom coverage could be explained by the fact that the TiN deposition was surface reaction controlled with an activation energy of ∼1.0 eV. AES analysis revealed the low carbon level (∼18 at. %) in TEMAT-sourced TiN films, which was ∼2× lower than that in TiN films prepared from tetrakis(diethylamido)titanium (TDEAT). We proposed the possible reaction mechanism responsible for the low carbon contents in the films, based on the byproduct gases detected by quadrupole mass spectrometer (QMS). TEMAT also produced better crystalline and less air-reactive films than tetrakis(dimethylamido)titanium (TDMAT). Consequently, the TEMAT compound can be a promisint precursor for MOCVD TiN.

Ta(CN) films were thermally deposited at low temperature (≤400°C) using single source pentakis(diethylamido)tantalum (PDEAT) as a precursor. The activation energy of the surface reaction is about 0.79 eV and the maximum deposition rate obtained is about 100 Å/min at 350°C. The resistivity of the as-deposited film decreases as the deposition temperature increases and the minimum value of resistivity obtained is 6000 µ Ω-cm for the sample deposited at 400°C. There is no aging effect of the film resistivity after air exposure. Major chemical elements in the films are identified as Ta, C, and N with some amounts of O by Auger electron spectroscopy (AES). Most of the carbon elements in the film is identified as bonded to Ta by X-ray photoelectron spectroscopy (XPS). The microstructural investigation using high resolution transmission electron microscopy (HRTEM) reveals a nanocrystalline phase with an average grain size of about 30 Å.

One of the most critical issues in manufacturing Cu-based integrated circuits (ICs) is to develop a suitable diffusion barrier material and deposition process. [1][2][3][4] Extensive work during the last decade has proven that Ta and its nitrides, such as Ta 2 N and TaN, show superior barrier properties against Cu metallization. However, most TaN layers tested so far have been deposited by reactive sputtering, 5-6 which does not yield sufficient conformal coverage to be applied in submicron generation devices. Therefore, a chemical vapor deposition (CVD) technique to deposit TaN films should be developed, and the barrier properties of those films should be tested for successful integration in Cu interconnects.There have been several attempts to develop a CVD-TaN process, which can be categorized into two regimes. One is by using halogen chemicals, such as TaCl 5 7 and TaBr 5 8 and the other is employing metallorganic (MO) source gases, such as (NEt 2 ) 3 TaϭNBu t [tertbutylimido(trisdiethylamido)tantalum, TBTDET)] 9 and Ta(NEt 2 ) 5 [pentakis(diethylamido)tantalum, PDEAT]. 10,11 In general, it is known that CVD deposition of TaN using halogen chemicals requires a high deposition temperature. For instance, CVD deposition of TaN using TaCl 5 , N 2 , and H 2 requires a deposition temperature higher than 900ЊC 7 which is too high to be applicable in an integrated circuit (IC) process. The deposition temperature is lowered by using TaBr 5 and NH 3 for the Ta and nitrogen source gases, respectively. Recently, it has been reported that the deposition temperature can be lowered to less than 450ЊC by using TaBr 5 , NH 3 , and H 2 source gases. 8 Another approach to lowering the deposition temperature is by using a single source of MO source gas as was demonstrated by Tsai et al., 9 Chiu et al., 10 and Jun et al. 11 However, the deposition temperature should be sufficiently high (>600ЊC) as to obtain a reasonable resistivity value (<1000 ⍀ cm). 9 The film produced inherently contains a high carbon concentration, especially when using a single MO source gas.In this study, TaN x films have been deposited using PDEAT and NH 3 source gases. The film properties such as resistivity, composition, crystal structure, and microstructure as a function of NH 3 flow rate have been investigated. The intention was to deposit a film with a low carbon concentration and with low resistivity by using NH 3 as a nitrogen source gas and test it as a diffusion barrier against Cu. This work was motivated from the well-documented works of MOCVDTiN in which the carbon concentration in the as-deposited film was significantly reduced by using NH 3 with MO source gases, such as tetrakis(dimethylamido)titanium (TDMAT) and tetrakis(diethylamido)titanium (TDEAT). 12-14 It is known that the transamination reaction occurs between the nitrogen in the MO source gas and the nitrogen in NH 3 . This yields a low resistivity TiN film with an extremely low carbon concentration. The same mechanism should apply to MOCVD-TaN since PDEAT and TDEAT have similar chemi...

Tantalum nitride (TaN) films were deposited by using pentakis(diethylamido)tantalum and ammonia. The activation energies of the surface reaction were obtained with the NH3 flow rate. In addition, the resistivity, composition, crystal structure, and microstructure were systematically studied with the NH3 flow rate from 0 to 25 sccm. The resistivity of the asdeposited film was decreased as the NH3 flow rate was increased, but it was increased at the NH3 flow rate of 25 sccm. The minimum value of resistivity is about 7000 μΩ-cm at the NH3 flow rate of 20 sccm. The carbon content in the film was decreased down to 1 at.% as the NH3 flow rate was increased up to 25 sccm by Auger electron spectroscopy. Rutherford backscattering spectrometry showed that the N/Ta ratio is about 1.75, which is not considerably changed with the NH3 flow rate. In spite of this high nitrogen content in the film, it was revealed that the fcc TaN was formed by x-ray diffractometry and transmission electron microscopy. The etch-pits test showed that 50-nm-thick TaN films deposited at the NH3 flow rate of 0 and 25 sccm prevented the diffusion of Cu into the Si substrate at the annealing condition of 500 °C and 550 °C for 1 hour, respectively. The step coverage was estimated as over 80 % at the NH3 flow rate of 0 sccm and below 10 % with the addition of NH3 in 0.5 μm × 1.5 μm contacts by cross-section scanning electron microscopy.