Improved electrical performances of plasma-enhanced atomic layer deposited TaCxNy films by adopting Ar∕H2 plasma

Eom

Electrochem. Solid-State Lett.

et al. 2011

TaC x films were deposited by plasma-enhanced atomic layer deposition (PEALD) at a wafer temperature of 300 C using a novel nitrogen-free Ta precursor, tris(neopentyl) tantalum dichloride, Ta[CH 2 C(CH 3 ) 3 ] 3 Cl 2 and H 2 plasma as the reactant. Self-limiting film growth was observed with both the precursor and reactant pulsing time. Both X-ray diffraction and electron diffraction analysis consistently showed that a cubic TaC phase formed, even though the film was Ta-rich TaC x (C/Ta ¼ $0.36). The film resistivity decreased with increasing H 2 plasma pulsing time from 900 to 375 X cm. In this study, a performance of TaC x as a diffusion barrier for Cu interconnects was evaluated. The results showed that the structure of Cu (100 nm)/ALD-TaC x (15 nm)/Si was stable after annealing at 650 C for 30 min.Tantalum (Ta)-based thin films, such as Ta, TaN x , TaC x and TaC x N y , have been investigated for decades for semiconductor microelectronic devices applications owing to their excellent properties, such as high electrical conductivity, chemical, mechanical and thermal stability. 1-6 Although the main applications of these materials are as a diffusion barrier for copper metallization, 1-5 they are also considered to be a metal gate with high-permittivity gate dielectrics. 6 For these applications, they need to be deposited uniformly at high aspect ratio (AR) structures with a conformal thickness as the demand for shrinking dimensions is increased. In addition, a deposition technique with high process controllability and large-area uniformity is needed. Atomic layer deposition (ALD) is a viable solution because ALD uses a self-limiting film growth mode through surface-saturated reactions, which enables atomicscale control of the film thickness and composition with excellent step coverage. 7 Currently, ALD of Ta-based films has attracted increasing attention for the preparation of Ta nitrides. The most critical issue in the TaN x -ALD process is to obtain highly conductive TaN films. Ta 3 N 5 , which is nitrogen-rich phase in the Ta-N binary system and a dielectric material, was deposited using TaCl 5 and NH 3 and its resistivity was as high as $200 X cm. 8 highly conductive TaN film can be deposited using an additional reducing agent, such as Zn (Ref. 8) or trimethyl aluminum (TMA), 9 but its resistivity was still high, from $900 to $1300 X cm. Moreover, small amounts of Zn impurities ($4 atom %) can cause severe problems if they diffused into the Si substrate. In addition, the use of inorganic precursors, such as TaCl 5 and TaBr 5 , has the potential problem of the incorporation of corrosive halogen elements in the film, particularly when the deposition temperature is as low as 400 C. 8,9 The successful deposition of low-resistivity TaN (q: 350-610 mX cm) with inorganic precursors of TaCl 5 (Ref. 10) and TaF 5 (Ref. 11) is possible using N 2 / H 2 plasma as a reducing agent of the precursors, in contrast to the highly-resistive Ta 3 N 5 growth by the reaction of TaCl 5 with molecular NH 3 .Ta nitride ALD was also ...

mentioning

confidence: 97%

mentioning

confidence: 99%

Plasma-Enhanced Atomic Layer Deposition of TaCx Films Using Tris(neopentyl) Tantalum Dichloride and H2 Plasma

Eom

Electrochem. Solid-State Lett.

et al. 2011

“…Figure (a) shows the binding energies of the C 1 s photoelectron. In the C 1 s spectra, an intensive peak centered at approximately ~282.7 eV was observed, which originates from the C–Ta chemical bonds of TaC x , suggesting that the incorporated C formed bonds mostly with Ta. The Ta 4 f XPS spectrum [Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Tantalum (Ta)‐based thin films, such as Ta, TaN x , TaC x , and TaC x N y , have been examined extensively for semiconductor microelectronic devices applications, such as diffusion barriers, capacitor electrodes, and gate electrodes . Among them, TaC x has attracted considerable attention because of its attractive properties, such as excellent chemical and thermal stability (Ta 2 C and TaC have melting points of 3330°C and 3985°C, respectively), and good electrical conductivity (~27 μΩ cm) .…”

Section: Introductionmentioning

confidence: 99%

“…ALD is a viable option because it involves a self‐limited film growth mode through surface‐saturated reactions, which enables atomic‐scale control of the film thickness and composition with excellent step coverage . In contrast to the extensive studies of Ta‐based nitrides ALD, there are few reports on TaC x ALD process . Plasma‐enhanced ALD (PEALD) Ta‐rich TaC x films with a growth rate of ~1 Å per cycle were deposited using an inorganic precursor and a carbon‐containing gas, but the process details were not reported .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

TaC_x Thin Films Prepared by Atomic Layer Deposition as Diffusion Barriers for Cu Metallization

et al. 2013

TaCx films were deposited by atomic layer deposition (ALD) using tris (neopentyl) tantalum dichloride, (Ta[CH2C(CH3)3]3Cl2) and H2 plasma as the precursor and reactant, respectively, at substrate temperatures ranging from 200°C to 400°C. The ALD–TaCx films with the formation of nanocrystalline structures and a rock‐salt phase were confirmed by X‐ray and electron diffraction. The ALD temperature window was found to be 225°C–300°C with a growth rate of ~0.11 nm per cycle. The resistivity of the ALD–TaCx films was dependent on the microstructural features, such as the grain size and crystallinity, as well as their composition (C/Ta ratio), and the presence of impurities in the films, which could be controlled by varying the deposition parameters, such as the deposition temperature and reactant pulse conditions. With increasing deposition temperature and reactant pulse time, Ta‐rich films with a low Cl impurity concentration and larger grain size were obtained. The film with a resistivity less than 400 μΩ cm was obtained at 300°C, which was within the ALD temperature window, by optimizing the H2 plasma pulse time. The step coverage of the film deposited at 300°C was approximately 100% over the trench structure (top opening width of 25 nm) with an aspect ratio of ~4.5. The performance of the ALD–TaCx films deposited under the optimized conditions was evaluated as a diffusion barrier for the Cu interconnects. The structure of Cu (100 nm)/ALD–TaCx (5 nm)/ Si was stable without the formation of copper silicide after annealing at 600°C for 30 min.

Trilayer Tunnel Selectors for Memristor Memory Cells

et al. 2015